Address latest comments after merge from master

Makefile

@@ -13,10 +13,11 @@ include Makefile.global
 
 all: extension
 
+ENSURE_SUBDIRS_EXIST := $(shell mkdir -p $(SUBDIRS))
+
 #build columnar only
 columnar:
 	$(MAKE) -C src/backend/columnar all
-	cp $(citus_top_builddir)/src/backend/columnar/columnar.so $(citus_top_builddir)/src/backend/distributed/
 # build extension
 extension: $(citus_top_builddir)/src/include/citus_version.h columnar
 	$(MAKE) -C src/backend/distributed/ all
@@ -33,7 +34,6 @@ install-headers: extension
 
 clean-extension:
 	$(MAKE) -C src/backend/distributed/ clean
-	rm -f $(citus_top_builddir)/src/backend/distributed/columnar.so
 	$(MAKE) -C src/backend/columnar/ clean
 clean-full:
 	$(MAKE) -C src/backend/distributed/ clean-full

src/backend/columnar/Makefile

@@ -1,22 +1,14 @@
 citus_subdir = src/backend/columnar
+citus_top_builddir = ../../..
 safestringlib_srcdir = $(citus_abs_top_srcdir)/vendor/safestringlib
 SUBDIRS = . safeclib
 SUBDIRS +=
 OBJS += \
-	$(patsubst $(citus_subdir)/%.c,%.o,$(foreach dir,$(SUBDIRS), $(sort $(wildcard $(citus_subdir)/$(dir)/*.c))))
+	$(patsubst $(citus_abs_srcdir)/%.c,%.o,$(foreach dir,$(SUBDIRS), $(sort $(wildcard $(citus_abs_srcdir)/$(dir)/*.c))))
 
 MODULE_big = columnar
 
 
 PG_CPPFLAGS += -I$(libpq_srcdir) -I$(safestringlib_srcdir)/include
 
-
-ifdef USE_PGXS
-PG_CONFIG = pg_config
-PGXS := $(shell $(PG_CONFIG) --pgxs)
-include $(PGXS)
-else
-subdir = src/backend/columnar
-top_builddir = ../../..
-include $(top_builddir)/Makefile.global
-endif
+include $(citus_top_builddir)/Makefile.global

src/backend/distributed/Makefile

@@ -36,7 +36,8 @@ all:
 
 NO_PGXS = 1
 
-SHLIB_LINK += $(libpq) columnar.so
+SHLIB_LINK += $(libpq) 
+SHLIB_LINK_INTERNAL += -L../columnar -l:columnar.so
 
 include $(citus_top_builddir)/Makefile.global