pgsql: Remove --disable-thread-safety and related code.

Remove --disable-thread-safety and related code.

All supported computers have either POSIX or Windows threads, and we no
longer have any automated testing of --disable-thread-safety. We define
a vestigial ENABLE_THREAD_SAFETY macro to 1 in ecpg_config.h in case it
is useful, but we no longer test it anywhere in PostgreSQL code, and
associated dead code paths are removed.

The Meson and perl-based Windows build scripts never had an equivalent
build option.

Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Reviewed-by: Peter Eisentraut <peter(at)eisentraut(dot)org>
Reviewed-by: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Discussion: https://postgr.es/m/CA%2BhUKGLtmexrpMtxBRLCVePqV_dtWG-ZsEbyPrYc%2BNBB2TkNsw%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/68a4b58eca032916e2aad78d63f717dcb147e906

Modified Files
--------------
configure | 54 ++--------------
configure.ac | 26 ++------
doc/src/sgml/installation.sgml | 13 ----
meson.build | 11 ----
src/Makefile.global.in | 1 -
src/bin/pgbench/pgbench.c | 22 +------
src/include/pg_config.h.in | 4 --
src/interfaces/ecpg/ecpglib/connect.c | 40 ------------
src/interfaces/ecpg/ecpglib/descriptor.c | 10 ---
src/interfaces/ecpg/ecpglib/ecpglib_extern.h | 2 -
src/interfaces/ecpg/ecpglib/execute.c | 2 -
src/interfaces/ecpg/ecpglib/memory.c | 7 ---
src/interfaces/ecpg/ecpglib/misc.c | 47 --------------
src/interfaces/ecpg/include/ecpg-pthread-win32.h | 3 -
src/interfaces/ecpg/include/ecpg_config.h.in | 5 +-
src/interfaces/ecpg/include/ecpglib.h | 2 -
src/interfaces/ecpg/include/meson.build | 3 +-
src/interfaces/ecpg/test/expected/thread-alloc.c | 43 ++++++-------
.../ecpg/test/expected/thread-descriptor.c | 22 +++----
src/interfaces/ecpg/test/expected/thread-prep.c | 71 ++++++++++------------
src/interfaces/ecpg/test/expected/thread-thread.c | 63 ++++++++-----------
.../ecpg/test/expected/thread-thread_implicit.c | 63 ++++++++-----------
src/interfaces/ecpg/test/thread/alloc.pgc | 9 ---
src/interfaces/ecpg/test/thread/descriptor.pgc | 8 +--
src/interfaces/ecpg/test/thread/prep.pgc | 9 ---
src/interfaces/ecpg/test/thread/thread.pgc | 9 ---
.../ecpg/test/thread/thread_implicit.pgc | 9 ---
src/interfaces/libpq/Makefile | 5 +-
src/interfaces/libpq/fe-connect.c | 4 --
src/interfaces/libpq/fe-exec.c | 4 --
src/interfaces/libpq/fe-print.c | 13 +---
src/interfaces/libpq/fe-secure-openssl.c | 17 +-----
src/interfaces/libpq/fe-secure.c | 26 +-------
src/interfaces/libpq/legacy-pqsignal.c | 4 +-
src/interfaces/libpq/libpq-int.h | 9 +--
src/makefiles/meson.build | 1 -
src/tools/msvc/Solution.pm | 3 +-
src/tools/msvc/ecpg_regression.proj | 2 +-
38 files changed, 137 insertions(+), 509 deletions(-)