Use one of not-null unique keys to identify rows when the target table doesn't

have a primary key. Some of users want to use not-null unique keys rather than
primary keys because postgres doesn't support REINDEX PRIMARY KEY CONCURRENTLY.

- Support 9.1dev.
- Improve Makefile to use PGXS automatically.

lib/Makefile

@@ -9,13 +9,21 @@ MODULE_big = pg_reorg
 DATA_built = pg_reorg.sql
 DATA = uninstall_pg_reorg.sql
 
+ifndef USE_PGXS
+top_builddir = ../../..
+makefile_global = $(top_builddir)/src/Makefile.global
+ifeq "$(wildcard $(makefile_global))" ""
+USE_PGXS = 1	# use pgxs if not in contrib directory
+endif
+endif
+
 ifdef USE_PGXS
-PGXS := $(shell pg_config --pgxs)
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
 include $(PGXS)
 else
-subdir = contrib/pg_reorg
-top_builddir = ../../..
-include $(top_builddir)/src/Makefile.global
+subdir = contrib/$(MODULE_big)
+include $(makefile_global)
 include $(top_srcdir)/contrib/contrib-global.mk
 endif