pgsql: Partially revert my patch of 2008-11-12 that installed a limit on

Log Message:
-----------
Partially revert my patch of 2008-11-12 that installed a limit on the number
of AND/OR clause branches that predtest.c would attempt to deal with. As
noted in bug #4721, that change disabled proof attempts for sizes of problems
that people are actually expecting it to work for. The original complaint
it was trying to solve was O(N^2) behavior for long IN-lists, so let's try
applying the limit to just ScalarArrayOpExprs rather than everything.
Another case of "foolish consistency" I fear.

Back-patch to 8.2, same as the previous patch was.

Modified Files:
--------------
pgsql/src/backend/optimizer/util:
predtest.c (r1.25 -> r1.26)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/predtest.c?r1=1.25&r2=1.26)