pgsql: Simplify gettimeofday() fallback logic.

Simplify gettimeofday() fallback logic.

There's no known supported system needing 1 argument gettimeofday()
support. The test for it was added a long time ago (92c6bf9775b). Remove.

Until now we tested whether a gettimeofday() fallback is needed when
targetting windows. Which lead to the odd result that HAVE_GETTIMEOFDAY only
being defined when targetting MinGW (which has gettimeofday() since at least
2007). As the fallback is specific to msvc, remove the configure code and
rename src/port/gettimeofday.c to src/port/win32gettimeofday.c.

While at it, also remove the definition of struct timezone, a forward
declaration of the struct is sufficient.

Reviewed-By: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220806000311.ywx65iuchvj4qn2k@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/922a8fa098404cbd5c6089e78eca4aebd828f847

Modified Files
--------------
config/c-library.m4                              | 24 ------------
configure                                        | 47 ------------------------
configure.ac                                     |  2 -
src/include/pg_config.h.in                       | 10 -----
src/include/port.h                               |  5 ---
src/include/port/win32_port.h                    | 15 +++-----
src/port/{gettimeofday.c => win32gettimeofday.c} |  4 +-
src/tools/msvc/Mkvcbuild.pm                      |  3 +-
src/tools/msvc/Solution.pm                       |  2 -
9 files changed, 9 insertions(+), 103 deletions(-)