Merge libraries from nearest ancestor.

This establishes a stub target with a property indicating the parent.
This allows library merging to walk the parents to the nearest ancestor
with a compatible target, which prevents stubs from being necessary
along the way.

Fixes llvm-mos#140.

fix #elseif typo causing wrong define (llvm-mos#135)

Co-authored-by: Xark <[email protected]>

Cx16 kernal support (llvm-mos#131)

* use void* vs unsigned int

* update cx16 kernal and add cbm kernal globals

* fix uint64_t printf warning

* add cx16 kernal wrappers and headers

* WIP cx16 kernal wrappers

* add kernal routine CINT

* rework for new llvm reg layout, needs more testing

* Squashed commit of the following:

commit f0b30a6
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 25 08:05:43 2023 +0200

    Update README.md to list all currently supported platforms

commit d3caa19
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 22:53:36 2023 +0200

    [PCE] Fix issues.

commit 2b05b08
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 22:35:24 2023 +0200

    [PCE] Remove pce_memcpy/pce_memmove/pce_memset first pass implementations.

    They are not suitable as a general replacement for memcpy/memmove/memset, as
    they stall interrupts while they are being executed.

    These can be reinstated in a separate PR, once the best way to expose this
    to the end user is evaluated.

commit 6dd6af1
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 22:27:50 2023 +0200

    [PCE] Downgrade virtual bank system to a much less complex physical bank offset mapping system.

commit 5763cf6
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 14:31:28 2023 +0200

    [PCE] Fix typo.

commit 82d1ee7
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 14:22:09 2023 +0200

    [PCE] Add pce_sgx_detect().

commit 8e38046
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 11:14:40 2023 +0200

    [PCE] Add PCE_FREQ_TO_TIMER define, fully derive its origin.

commit f176029
Author: Adrian Siekierka <[email protected]>
Date:   Sat Jun 24 11:04:19 2023 +0200

    [PCE] Add missing newlines.

commit eb8c933
Author: Adrian Siekierka <[email protected]>
Date:   Thu Jun 22 23:24:00 2023 +0200

    [PCE] Fix pce_rom_vbankN_call safety.

commit 71876fc
Author: Adrian Siekierka <[email protected]>
Date:   Thu Jun 22 20:55:58 2023 +0200

    [PCE] Add pce_rom_vbankN_bank getter

commit 5e74a93
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 22:17:52 2023 +0200

    [PCE] Fix set_resolution optimization regression, add pce_sgx_vdc_init

commit 101d0bc
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 21:58:37 2023 +0200

    [PCE] Add support for two VDCs in vdc.c.

commit dbd398e
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 21:39:30 2023 +0200

    [PCE] Add SuperGrafx MMIO defines.

commit d61c0a5
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 18:10:36 2023 +0200

    [PCE] Adjust color-cycle.c example to use interrupts.

commit b802a2c
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 17:37:41 2023 +0200

    [PCE] Finish writing initial VDC functions.

commit 07e4b21
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 17:17:06 2023 +0200

    [PCE] Bugfixes, add VDC/VCE/PSG reset routines.

commit dabf4c8
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 16:48:29 2023 +0200

    [PCE] Further unify VBank naming conventions.

commit 3f9a307
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 01:03:59 2023 +0200

    [PCE] Implement VDC enable/disable routines, fixes.

commit 5ddc148
Author: Adrian Siekierka <[email protected]>
Date:   Wed Jun 21 00:17:30 2023 +0200

    [PCE] Implement VDC/VCE copy routines.

commit c8f201a
Author: Adrian Siekierka <[email protected]>
Date:   Tue Jun 20 22:01:05 2023 +0200

    [PCE] Add pce_memop, minor cleanup.

commit bc2bf2f
Author: Adrian Siekierka <[email protected]>
Date:   Tue Jun 20 20:50:05 2023 +0200

    [PCE] Add VDC resolution configuration functions, PCE_ROM_FIXED_BANK_SIZE define

commit cc36ab5
Author: Adrian Siekierka <[email protected]>
Date:   Tue Jun 20 19:00:21 2023 +0200

    [PCE] Fix hardware stack init regression.

commit 7e9981b
Author: Adrian Siekierka <[email protected]>
Date:   Tue Jun 20 18:58:18 2023 +0200

    [PCE] Implement optimized zero-bss handlers.

commit 4af4ac9
Author: Adrian Siekierka <[email protected]>
Date:   Tue Jun 20 18:33:32 2023 +0200

    [PCE] Support changing the size of virtual bank 0.

commit 6f32c9e
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 22:46:18 2023 +0200

    [PCE] Add optimized memcpy/memmove/memset implementations.

commit 7fd8bca
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 20:38:00 2023 +0200

    [PCE] Document libpce functions.

commit 6d91920
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 20:18:41 2023 +0200

    [PCE] Add Arcade Card and Super System Card hardware defines.

commit 864f1a7
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 19:54:02 2023 +0200

    [PCE] Add to README.

commit 06c447d
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 19:18:27 2023 +0200

    [PCE] Fix banking example.

commit a343c94
Author: Adrian Siekierka <[email protected]>
Date:   Mon Jun 19 18:53:59 2023 +0200

    [PCE] vbank system refactors, add support for SGX RAM

commit 673b243
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 23:24:32 2023 +0200

    [PCE] Initial interrupt implementation.

commit f2d4373
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 22:34:21 2023 +0200

    [PCE] Fix soft stack location.

commit 9116694
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 21:51:57 2023 +0200

    [PCE] Adjust linkscript symbol convention to match NES target

commit bf1618f
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 20:17:33 2023 +0200

    [PCE] Adjust linkscript symbols for llvm-mlb.

commit 9acebcf
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 18:10:01 2023 +0200

    [PCE] Add pce_vbank_call helper routines.

commit 0d05f4d
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 15:48:59 2023 +0200

    [PCE] Clean up bank.h/.c/.S after figuring out the banking system.

commit 33566e1
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 15:41:05 2023 +0200

    [PCE] Optimize vbank_set for 8KB vbanks, fix PCE_VBANK_DECLARE for >8KB vbanks.

commit 3aed2ec
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 15:22:28 2023 +0200

    [PCE] Banking improvements.

    - Provide missing one-bank getters and setters.
    - Use C where using ASM provides no "bank chain" size advantage to allow for
      inlining opportunities.

commit 219b83c
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 15:03:05 2023 +0200

    [PCE] Introduce banking system.

commit fb2f650
Author: Adrian Siekierka <[email protected]>
Date:   Sun Jun 18 12:35:15 2023 +0200

    Initial pce (PC Engine) platform.

    Banking is not yet implemented, so limited to eight-kilobyte ROMs.
    This will be improved soon...

* working nicely saving extra regs per X16 docs

* new funcs, cc65 funcs, new tests, some debugging

* spelling fix, consistent license comments

* Cleanup PR

* Revert erroneous PCE changes

* Merge branch 'main' into cx16_kernal_support

---------

Co-authored-by: Xark <[email protected]>
Co-authored-by: Daniel Thornburgh <[email protected]>

libc improvements: ctype, errno, div/ldiv/lldiv, strerror; math.h, ti…

…me.h, wchar.h stubs (llvm-mos#128)

Update README.md to list all currently supported platforms

Unify soft stack initialization. (llvm-mos#122)

The intended value of the soft stack pointer is the byte *after* the top-most
(last) writable byte in the stack area. This matches the convention used by
targets "dodo" and "sim"; therefore, this commit fixes it for all other
targets.

Correct elftocpm62 headers (missing cstdint)

Initial support for a PET target (llvm-mos#109)

* Initial support for a PET target

* Created user-definable symbol for RAM size to add support for 8k and 16k PETs

* Added variables to the commodore linker file to be defined in the concrete targets specifying the start and end of the free zero page

* Pushed zero page flag in clang.cfg down from commodore into concrete targets as all targets no longer share the same amount of free zero page

* Added mention of PET support to README

Remove unneeded OVERLAY tags.

RAM shouldn't have a separate LMA region.

This was intended to be a way to track the bank of PRG-RAM values in a
mapper-independent way, but it just adds too much complexity to the
linker scripts, since RAM logically shouldn't have a LMA at all. This
caused the addresses to get mismatched, and its better to just not deal
with this.