Setup GPHOME_LOADERS environment and script (#10107)

GPHOME_LOADERS and greenplum_loaders_path.sh are still requried by some users.
So export GPHOME_LOADERS as GPHOME_CLIENTS and link greenplum_loaders_path.sh
to greenplum_clients_path.sh for compatible

concourse/scripts/compile_gpdb.bash

@@ -182,6 +182,9 @@ function export_gpdb_clients() {
     mkdir -p bin/ext/gppylib
     cp ${GREENPLUM_INSTALL_DIR}/lib/python/gppylib/__init__.py ./bin/ext/gppylib
     cp  ${GREENPLUM_INSTALL_DIR}/lib/python/gppylib/gpversion.py ./bin/ext/gppylib
+    # GPHOME_LOADERS and greenplum_loaders_path.sh are still requried by some users
+    # So link greenplum_loaders_path.sh to greenplum_clients_path.sh for compatible
+    ln -sf greenplum_clients_path.sh greenplum_loaders_path.sh
     chmod -R 755 .
     tar -czf "${TARBALL}" ./*
   popd

gpAux/client/scripts/greenplum_clients_path.sh

@@ -2,7 +2,10 @@ GPHOME_CLIENTS=`pwd`
 PATH=${GPHOME_CLIENTS}/bin:${GPHOME_CLIENTS}/ext/python/bin:${PATH}
 PYTHONPATH=${GPHOME_CLIENTS}/bin/ext:${PYTHONPATH}
 
+# Export GPHOME_LOADERS for GPDB5 compatible
+GPHOME_LOADERS=${GPHOME_CLIENTS}
 export GPHOME_CLIENTS
+export GPHOME_LOADERS
 export PATH
 export PYTHONPATH