pgsql: Rearrange backend startup sequence so that ShmemIndexLock can

Log Message:
-----------
Rearrange backend startup sequence so that ShmemIndexLock can become
an LWLock instead of a spinlock.  This hardly matters on Unix machines
but should improve startup performance on Windows (or any port using
EXEC_BACKEND).  Per previous discussion.

Modified Files:
--------------
    pgsql/src/backend/bootstrap:
        bootstrap.c (r1.209 -> r1.210)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/bootstrap/bootstrap.c.diff?r1=1.209&r2=1.210)
    pgsql/src/backend/postmaster:
        autovacuum.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/autovacuum.c.diff?r1=1.8&r2=1.9)
        pgarch.c (r1.18 -> r1.19)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgarch.c.diff?r1=1.18&r2=1.19)
        pgstat.c (r1.118 -> r1.119)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c.diff?r1=1.118&r2=1.119)
        postmaster.c (r1.476 -> r1.477)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c.diff?r1=1.476&r2=1.477)
        syslogger.c (r1.21 -> r1.22)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/syslogger.c.diff?r1=1.21&r2=1.22)
    pgsql/src/backend/storage/ipc:
        ipci.c (r1.80 -> r1.81)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/ipci.c.diff?r1=1.80&r2=1.81)
        shmem.c (r1.89 -> r1.90)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/shmem.c.diff?r1=1.89&r2=1.90)
    pgsql/src/backend/storage/lmgr:
        proc.c (r1.170 -> r1.171)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/proc.c.diff?r1=1.170&r2=1.171)
    pgsql/src/backend/tcop:
        postgres.c (r1.474 -> r1.475)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.474&r2=1.475)
    pgsql/src/backend/utils/init:
        postinit.c (r1.159 -> r1.160)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/init/postinit.c.diff?r1=1.159&r2=1.160)
    pgsql/src/include/storage:
        lwlock.h (r1.24 -> r1.25)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lwlock.h.diff?r1=1.24&r2=1.25)
        pg_shmem.h (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/pg_shmem.h.diff?r1=1.16&r2=1.17)
        proc.h (r1.85 -> r1.86)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/proc.h.diff?r1=1.85&r2=1.86)
        shmem.h (r1.45 -> r1.46)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/shmem.h.diff?r1=1.45&r2=1.46)