Even in SCL world we so far lived fine with --disable-rpath.  But in some
usecases, SCLized libpqwalreceiver.so needs to have RPATH set.

Resolves: rhbz#1550567

diff --git a/src/backend/replication/libpqwalreceiver/Makefile b/src/backend/replication/libpqwalreceiver/Makefile
index 75b0e2b..69b0de6 100644
--- a/src/backend/replication/libpqwalreceiver/Makefile
+++ b/src/backend/replication/libpqwalreceiver/Makefile
@@ -15,7 +15,11 @@ include $(top_builddir)/src/Makefile.global
 override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
 
 OBJS = libpqwalreceiver.o $(WIN32RES)
-SHLIB_LINK_INTERNAL = $(libpq)
+# Force rpath to be used even though we disable it everywhere else.  This is
+# needed because the 'libpqwalreceiver.so' is loaded into process (with
+# CREATE SUBSCRIPTION) which has dropped the $LD_LIBRARY_PATH variable from the
+# parent $bindir/postgress process.
+SHLIB_LINK_INTERNAL = $(libpq) $(rpath)
 SHLIB_LINK = $(filter -lintl, $(LIBS))
 SHLIB_PREREQS = submake-libpq
 PGFILEDESC = "libpqwalreceiver - receive WAL during streaming replication"