pgsql: Revert "Distinguish printf-like functions that support %m fromt

Revert "Distinguish printf-like functions that support %m from those that don't."

This reverts commit 3a60c8ff892a8242b907f44702bfd9f1ff877d45.  Buildfarm
results show that that caused a whole bunch of new warnings on platforms
where gcc believes the local printf to be non-POSIX-compliant.  This
problem outweighs the hypothetical-anyway possibility of getting warnings
for misuse of %m.  We could use gnu_printf archetype when we've substituted
src/port/snprintf.c, but that brings us right back to the problem of not
getting warnings for %m.

A possible answer is to attack it in the other direction by insisting
that %m support be included in printf's feature set, but that will take
more investigation.  In the meantime, revert the previous change, and
update the comment for PGAC_C_PRINTF_ARCHETYPE to more fully explain
what's going on.

Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/46b5e7c4b5befbf6ac86d827a3a58f1f02c7338e

Modified Files
--------------
config/c-compiler.m4       | 20 +++++++++++++-------
configure                  |  6 +++---
src/include/c.h            |  6 +-----
src/include/pg_config.h.in |  4 ++--
src/include/utils/elog.h   | 30 +++++++++++++++---------------
5 files changed, 34 insertions(+), 32 deletions(-)