Fix for hang after postmaster restart. Add new proc_exit and

src/backend/bootstrap/bootstrap.c

src/backend/commands/async.c

src/backend/libpq/pqcomm.c

src/backend/postmaster/postmaster.c

src/backend/storage/ipc/ipc.c

src/backend/storage/ipc/ipci.c

src/backend/storage/ipc/shmem.c

src/backend/storage/ipc/sinvaladt.c

src/backend/storage/lmgr/lock.c

src/backend/storage/lmgr/multi.c

src/backend/storage/lmgr/proc.c

src/backend/storage/smgr/smgr.c

src/backend/tcop/postgres.c

src/backend/utils/error/elog.c

src/backend/utils/error/exc.c

src/backend/utils/init/miscinit.c

src/backend/utils/init/postinit.c

src/include/storage/ipc.h