mentioned before the system directories.
-I$(libpq_srcdir) $(CPPFLAGS)
override CFLAGS += $(PTHREAD_CFLAGS)
-override LDFLAGS := -L../../ecpglib -L../../pgtypeslib $(LDFLAGS)
-override LIBS := -lecpg -lpgtypes $(LIBS) $(PTHREAD_LIBS)
+override LDFLAGS := -L../../ecpglib -L../../pgtypeslib $(filter-out -l%, $(libpq)) $(LDFLAGS)
+override LIBS := -lecpg -lpgtypes $(filter -l%, $(libpq)) $(LIBS) $(PTHREAD_LIBS)
ECPG = ../../preproc/ecpg --regression -I$(srcdir)/../../include