pgsql: Promote pg_dumpall shell/connstr quoting functions to src/fe_uti

Promote pg_dumpall shell/connstr quoting functions to src/fe_utils.

Rename these newly-extern functions with terms more typical of their new
neighbors. No functional changes; a subsequent commit will use them in
more places. Back-patch to 9.1 (all supported versions). Back branches
lack src/fe_utils, so instead rename the functions in place; the
subsequent commit will copy them into the other programs using them.

Security: CVE-2016-5424

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/41f18f021a0882eccbeca62e2ed4b66c6b96e9c9

Modified Files
--------------
src/bin/pg_dump/pg_dumpall.c | 158 ++----------------------------------
src/fe_utils/string_utils.c | 143 ++++++++++++++++++++++++++++++++
src/include/fe_utils/string_utils.h | 7 +-
src/port/system.c | 3 +-
4 files changed, 157 insertions(+), 154 deletions(-)