Fix quoting in the add_to_path Makefile macro.
Fix quoting in the add_to_path Makefile macro.

The previous quoting caused "make -C src/bin check" to ignore, rather
than add to, any LD_LIBRARY_PATH content from the environment.
Back-patch to 9.4, where the macro was introduced.

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