Add postgres_fdw contrib module.

There's still a lot of room for improvement, but it basically works,
and we need this to be present before we can do anything much with the
writable-foreign-tables patch.  So let's commit it and get on with testing.

Shigeru Hanada, reviewed by KaiGai Kohei and Tom Lane

Author: tglsfdc

contrib/Makefile

@@ -43,6 +43,7 @@ SUBDIRS = \
 		pgcrypto	\
 		pgrowlocks	\
 		pgstattuple	\
+		postgres_fdw	\
 		seg		\
 		spi		\
 		tablefunc	\

contrib/postgres_fdw/.gitignore

@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/

contrib/postgres_fdw/Makefile

@@ -0,0 +1,27 @@
+# contrib/postgres_fdw/Makefile
+
+MODULE_big = postgres_fdw
+OBJS = postgres_fdw.o option.o deparse.o connection.o
+
+PG_CPPFLAGS = -I$(libpq_srcdir)
+SHLIB_LINK = $(libpq)
+SHLIB_PREREQS = submake-libpq
+
+EXTENSION = postgres_fdw
+DATA = postgres_fdw--1.0.sql
+
+REGRESS = postgres_fdw
+
+# the db name is hard-coded in the tests
+override USE_MODULE_DB =
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/postgres_fdw
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif