pgsql: Remove GUC USERLIMIT variable category, making the affected

Log Message:
-----------
Remove GUC USERLIMIT variable category, making the affected variables
plain SUSET instead. Also delay processing of options received in
client connection request until after we know if the user is a superuser,
so that SUSET values can be set that way by legitimate superusers.
Per recent discussion.

Modified Files:
--------------
pgsql/doc/src/sgml:
runtime.sgml (r1.291 -> r1.292)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/runtime.sgml.diff?r1=1.291&r2=1.292)
pgsql/src/backend/bootstrap:
bootstrap.c (r1.195 -> r1.196)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/bootstrap/bootstrap.c.diff?r1=1.195&r2=1.196)
pgsql/src/backend/postmaster:
postmaster.c (r1.437 -> r1.438)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c.diff?r1=1.437&r2=1.438)
pgsql/src/backend/tcop:
postgres.c (r1.436 -> r1.437)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.436&r2=1.437)
pgsql/src/backend/utils/init:
postinit.c (r1.137 -> r1.138)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/init/postinit.c.diff?r1=1.137&r2=1.138)
pgsql/src/backend/utils/misc:
guc.c (r1.248 -> r1.249)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.248&r2=1.249)
pgsql/src/include:
miscadmin.h (r1.172 -> r1.173)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/miscadmin.h.diff?r1=1.172&r2=1.173)
pgsql/src/include/tcop:
tcopprot.h (r1.71 -> r1.72)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/tcop/tcopprot.h.diff?r1=1.71&r2=1.72)
pgsql/src/include/utils:
guc.h (r1.55 -> r1.56)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/guc.h.diff?r1=1.55&r2=1.56)