pgsql: Remove configure switch --disable-strong-random

Remove configure switch --disable-strong-random

This removes a portion of infrastructure introduced by fe0a0b5 to allow
compilation of Postgres in environments where no strong random source is
available, meaning that there is no linking to OpenSSL and no
/dev/urandom (Windows having its own CryptoAPI).  No systems shipped
this century lack /dev/urandom, and the buildfarm is actually not
testing this switch at all, so just remove it.  This simplifies
particularly some backend code which included a fallback implementation
using shared memory, and removes a set of alternate regression output
files from pgcrypto.

Author: Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20181230063219.GG608@paquier.xyz

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/1707a0d2aa6b2bcfe78f63836c769943a1a6b9e0

Modified Files
--------------
configure                                          |  65 +---
configure.in                                       |  42 +-
contrib/pgcrypto/expected/pgp-compression_1.out    |  42 --
contrib/pgcrypto/expected/pgp-decrypt_1.out        | 424 ---------------------
contrib/pgcrypto/expected/pgp-encrypt_1.out        | 161 --------
contrib/pgcrypto/expected/pgp-pubkey-encrypt_1.out |  62 ---
contrib/pgcrypto/pgcrypto.c                        |  11 +-
contrib/pgcrypto/pgp-encrypt.c                     |  14 +-
contrib/pgcrypto/pgp-mpi-internal.c                |   6 +-
contrib/pgcrypto/pgp-pubenc.c                      |   9 +-
contrib/pgcrypto/pgp-s2k.c                         |   7 +-
contrib/pgcrypto/px-crypt.c                        |   3 +-
contrib/pgcrypto/px.c                              |  10 +-
doc/src/sgml/installation.sgml                     |  24 +-
doc/src/sgml/monitoring.sgml                       |   6 +-
src/Makefile.global.in                             |   1 -
src/backend/access/transam/xlog.c                  |   3 +-
src/backend/libpq/auth-scram.c                     |   5 +-
src/backend/libpq/auth.c                           |   5 +-
src/backend/postmaster/postmaster.c                |  62 +--
src/backend/storage/ipc/ipci.c                     |   3 -
src/backend/storage/lmgr/lwlocknames.txt           |   5 +-
src/backend/utils/adt/float.c                      |   3 +-
src/backend/utils/misc/Makefile                    |   6 +-
src/backend/utils/misc/backend_random.c            | 158 --------
src/bin/pgbench/pgbench.c                          |   6 +-
src/include/pg_config.h.in                         |   3 -
src/include/pg_config.h.win32                      |   3 -
src/include/port.h                                 |   7 +-
src/include/utils/backend_random.h                 |  19 -
src/interfaces/libpq/fe-auth-scram.c               |  62 +--
src/port/Makefile                                  |   6 +-
32 files changed, 60 insertions(+), 1183 deletions(-)