Add missing symlinked testcode to .gitignore
Add missing symlinked testcode to .gitignore

The GPTest.pm file is symlinked as a requirement for gpdiff, add
to ignore.

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