pgsql-server: Remove postgresql.conf of 'info' as a valid

Log Message:
-----------
Remove postgresql.conf of 'info' as a valid client_min_messages level.

Modified Files:
--------------
pgsql-server/doc/src/sgml:
plpgsql.sgml (r1.39 -> r1.40)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/plpgsql.sgml.diff?r1=1.39&r2=1.40)
pgsql-server/src/backend/utils/misc:
guc.c (r1.215 -> r1.216)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/misc/guc.c.diff?r1=1.215&r2=1.216)
postgresql.conf.sample (r1.114 -> r1.115)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/misc/postgresql.conf.sample.diff?r1=1.114&r2=1.115)