[lldb/DWARF] Downgrade the "parent of variable is not CU" error (llvm#108806)

This can legitimately happen for static function-local variables with a
non-manual dwarf index. According to the DWARF spec, these variables
should be (and are) included in the compiler generated indexes, but they
are ignored by our manual index. Encountering them does not indicate any
sort of error.

The error message is particularly annoying due to a combination of the
fact that we don't cache negative hits (so we print it every time we
encounter it), VSCode's aggresive tab completion (which attempts a
lookup after every keypress) and the fact that some low-level libraries
(e.g. tcmalloc) have several local variables called "v". The result is a
console full of error messages everytime you type "v ".

We already have tests (e.g. find-basic-variable.cpp), which check that
these variables are not included in the result (and by extension, that
their presence does not crash lldb). It would be possible to extend it
to make sure it does *not* print this error message, but it doesn't seem
like it would be particularly useful.

Author: labath

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

@@ -3828,10 +3828,9 @@ void SymbolFileDWARF::ParseAndAppendGlobalVariable(
     break;
 
   default:
-    GetObjectFile()->GetModule()->ReportError(
-        "didn't find appropriate parent DIE for variable list for {0:x8} "
-        "{1} ({2}).\n",
-        die.GetID(), DW_TAG_value_to_name(die.Tag()), die.Tag());
+    LLDB_LOG(GetLog(DWARFLog::Lookups),
+             "{0} '{1}' ({2:x8}) is not a global variable - ignoring", tag,
+             die.GetName(), die.GetID());
     return;
   }