Обсуждение: pgsql: Revert "Consistently test for in-use shared memory."

Revert "Consistently test for in-use shared memory."

This reverts commits 2f932f71d9f2963bbd201129d7b971c8f5f077fd,
16ee6eaf80a40007a138b60bb5661660058d0422 and
6f0e190056fe441f7cf788ff19b62b13c94f68f3.  The buildfarm has revealed
several bugs.  Back-patch like the original commits.

Discussion: https://postgr.es/m/20190404145319.GA1720877@rfd.leadboat.com

Branch
------
REL9_5_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/9ec582b64d69fcd103e8a3bc13a621ca376db921

Modified Files
--------------
src/backend/port/sysv_shmem.c       | 257 +++++++++++++++---------------------
src/backend/port/win32_shmem.c      |   7 +-
src/backend/postmaster/postmaster.c |  12 +-
src/backend/storage/ipc/ipci.c      |  14 +-
src/backend/utils/init/postinit.c   |   6 +-
src/include/storage/ipc.h           |   2 +-
src/include/storage/pg_shmem.h      |   6 +-
7 files changed, 138 insertions(+), 166 deletions(-)