pgsql-server: fmgr_security_definer had better do a PG_TRY to ensure the

Log Message:
-----------
fmgr_security_definer had better do a PG_TRY to ensure the outer userid
is restored on error exit.

Modified Files:
--------------
pgsql-server/src/backend/utils/fmgr:
fmgr.c (r1.84 -> r1.85)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/fmgr/fmgr.c.diff?r1=1.84&r2=1.85)