pgsql: Change the signaling of end-of-recovery.

Log Message:
-----------
Change the signaling of end-of-recovery. Startup process now indicates end
of recovery by exiting with exit code 0, like in previous releases. Per
Tom's suggestion.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xlog.c (r1.331 -> r1.332)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.331&r2=1.332)
    pgsql/src/backend/postmaster:
        postmaster.c (r1.572 -> r1.573)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c?r1=1.572&r2=1.573)
    pgsql/src/include/storage:
        pmsignal.h (r1.22 -> r1.23)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/pmsignal.h?r1=1.22&r2=1.23)
        proc.h (r1.111 -> r1.112)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/proc.h?r1=1.111&r2=1.112)