pgsql: Don't try to remove duplicate OR-subclauses in

Log Message:
-----------
Don't try to remove duplicate OR-subclauses in create_bitmap_subplan and
make_restrictinfo_from_bitmapqual. The likelihood of finding duplicates
seems much less than in the AND-subclause case, and the cost much higher,
because OR lists with hundreds or even thousands of subclauses are not
uncommon. Per discussion with Ilia Kantor and andrew@supernews.

Modified Files:
--------------
pgsql/src/backend/optimizer/plan:
createplan.c (r1.199 -> r1.200)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/createplan.c.diff?r1=1.199&r2=1.200)
pgsql/src/backend/optimizer/util:
restrictinfo.c (r1.39 -> r1.40)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/restrictinfo.c.diff?r1=1.39&r2=1.40)