pgsql: Fix all the server-side SIGQUIT handlers (grumble ...

Log Message:
-----------
Fix all the server-side SIGQUIT handlers (grumble ... why so many identical
copies?) to ensure they really don't run proc_exit/shmem_exit callbacks,
as was intended.  I broke this behavior recently by installing atexit
callbacks without thinking about the one case where we truly don't want
to run those callback functions.  Noted in an example from Dave Page.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xlog.c (r1.339 -> r1.340)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.339&r2=1.340)
    pgsql/src/backend/postmaster:
        autovacuum.c (r1.94 -> r1.95)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/autovacuum.c?r1=1.94&r2=1.95)
        bgwriter.c (r1.57 -> r1.58)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/bgwriter.c?r1=1.57&r2=1.58)
        walwriter.c (r1.5 -> r1.6)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/walwriter.c?r1=1.5&r2=1.6)
    pgsql/src/backend/storage/ipc:
        ipc.c (r1.103 -> r1.104)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/ipc.c?r1=1.103&r2=1.104)
    pgsql/src/backend/tcop:
        postgres.c (r1.565 -> r1.566)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c?r1=1.565&r2=1.566)