pgsql: Remove configure probe for sys/resource.h and refactor.

Remove configure probe for sys/resource.h and refactor.

<sys/resource.h> is in SUSv2 and is on all targeted Unix systems. We
have a replacement for getrusage() on Windows, so let's just move its
declarations into src/include/port/win32/sys/resource.h so that we can
use a standard-looking #include. Also remove an obsolete reference to
CLK_TCK. Also rename src/port/getrusage.c to win32getrusage.c,
following the convention for Windows-only fallback code.

Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/CA%2BhUKG%2BL_3brvh%3D8e0BW_VfX9h7MtwgN%3DnFHP5o7X2oZucY9dg%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/36b3d52459aecd4f8bc39a4604e42186c48aa9d2

Modified Files
--------------
configure | 14 +++++++-------
configure.ac | 3 +--
src/backend/storage/file/fd.c | 4 +---
src/backend/tcop/postgres.c | 10 ++--------
src/bin/pg_ctl/pg_ctl.c | 6 ++----
src/bin/pgbench/pgbench.c | 2 --
src/include/pg_config.h.in | 3 ---
src/include/port/win32/sys/resource.h | 20 +++++++++++++++++++
src/include/rusagestub.h | 31 ------------------------------
src/include/utils/pg_rusage.h | 7 +------
src/port/{getrusage.c => win32getrusage.c} | 11 +++--------
src/test/regress/pg_regress.c | 7 ++-----
src/tools/msvc/Mkvcbuild.pm | 3 ++-
src/tools/msvc/Solution.pm | 1 -
src/tools/pginclude/cpluspluscheck | 5 +----
src/tools/pginclude/headerscheck | 4 ----
16 files changed, 42 insertions(+), 89 deletions(-)