Fix win32setlocale.c const-related warnings.
Fix win32setlocale.c const-related warnings.

Back-patch to 9.2, like commit db29620d4d16e08241f965ccd70d0f65883ff0de.

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