Fix BLD_ARCH conditional

The format of the `findstring` function is `$(findstring find,in)` where
it searches `in` for occurences of `find`. The value of BLD_ARCH for
RHEL7 is rhel7_x86_64 and will never be found in `rhel6 rhel7`. This
commit changes the conditional to search for `rhel` in the value of
`BLD_ARCH` and if it is found, set the custom LDFLAGS.

[#171588911]
Co-authored-by: NBradford D. Boyle <bboyle@pivotal.io>
Co-authored-by: NXin Zhang <xzhang@pivotal.io>

gpAux/Makefile

@@ -253,7 +253,9 @@ ifdef ADDON_DIR
 CONFIGFLAGS+=ADDON_DIR=$(ADDON_DIR)
 endif
 
-ifneq "$(findstring $(BLD_ARCH),rhel6 rhel7)" ""
+# if $BLD_ARCH is rhel6_x86_64 of rhel7_x86_64
+# compile with relative rpath
+ifeq "$(findstring rhel,$(BLD_ARCH))" "rhel"
 CONFIGFLAGS+= --disable-rpath
 CONFIGFLAGS+= LDFLAGS='-Wl,--enable-new-dtags -Wl,-rpath,\$$$$ORIGIN/../lib'
 CONFIGFLAGS+= LDFLAGS_SL='-Wl,--enable-new-dtags -Wl,-rpath,\$$$$ORIGIN/../lib'
@@ -340,10 +342,10 @@ BLD_GPDB_BUILDSET=$($(BLD_ARCH)_GPDB_BUILDSET)
 # set default build steps
 define BUILD_STEPS
 	@rm -rf $(INSTLOC)
-	if [ "$(findstring $(BLD_ARCH),rhel6 rhel7)" = "" ]; then \
-	  cd $(BUILDDIR) && $(MAKE) $(PARALLEL_MAKE_OPTS) install; \
-	else \
+	if [ "$(findstring rhel,$(BLD_ARCH))" = "rhel" ]; then \
 	  cd $(BUILDDIR) && PYGRESQL_LDFLAGS='-Wl,-rpath,\$$$$ORIGIN/../../../lib -Wl,--enable-new-dtags' $(MAKE) $(PARALLEL_MAKE_OPTS) install; \
+	else \
+	  cd $(BUILDDIR) && $(MAKE) $(PARALLEL_MAKE_OPTS) install; \
 	fi \
 	#@$(MAKE) greenplum_path INSTLOC=$(INSTLOC)
 	#@$(MAKE) mgmtcopy INSTLOC=$(INSTLOC)