Make the AIX case of Makefile.shlib safe for parallel make.
Make the AIX case of Makefile.shlib safe for parallel make.

Use our typical approach, from src/backend/parser.  Back-patch to 9.1
(all supported versions).

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