Make orafce build without PGXS
Make orafce build without PGXS

While there is a target in gpAux/extensions for building orafuncs,
we might as well allow it to be built without PGXS as well which is
handy for quick compile tests. Set the correct path to the builddir
such that Makefile dependencies can be picked up.

jmcatamney/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,edespino/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,adam8157/gpdb,50wu/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,50wu/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,edespino/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,lisakowen/gpdb,edespino/gpdb,xinzweb/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,lisakowen/gpdb,ashwinstar/gpdb,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,50wu/gpdb,50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,Chibin/gpdb,xinzweb/gpdb,edespino/gpdb,edespino/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,edespino/gpdb,lisakowen/gpdb,Chibin/gpdb,xinzweb/gpdb,Chibin/gpdb,edespino/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,Chibin/gpdb,Chibin/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,adam8157/gpdb,edespino/gpdb,Chibin/gpdb,Chibin/gpdb,lisakowen/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,Chibin/gpdb,jmcatamney/gpdb,edespino/gpdb,yuanzhao/gpdb,adam8157/gpdb,50wu/gpdb,50wu/gpdb,lisakowen/gpdb,Chibin/gpdb,yuanzhao/gpdb,edespino/gpdb,jmcatamney/gpdb,Chibin/gpdb,lisakowen/gpdb