pgsql: Actually, nodeBitmapIndexscan.c doesn't need to create a standard

Log Message:
-----------
Actually, nodeBitmapIndexscan.c doesn't need to create a standard
ExprContext at all, since it never evaluates any qual or tlist expressions.

Modified Files:
--------------
pgsql/src/backend/executor:
nodeBitmapIndexscan.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeBitmapIndexscan.c.diff?r1=1.4&r2=1.5)