fix pg_buffercache install error

contrib/pg_buffercache/Makefile

@@ -1,8 +1,5 @@
 # contrib/pg_buffercache/Makefile
 
-MODULE_big = pg_buffercache
-OBJS = pg_buffercache_pages.o
-
 EXTENSION = pg_buffercache
 DATA = pg_buffercache--1.0.sql pg_buffercache--unpackaged--1.0.sql
 

contrib/pg_buffercache/pg_buffercache--1.0.sql

@@ -3,18 +3,9 @@
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION pg_buffercache" to load this file. \quit
 
--- Register the function.
-CREATE FUNCTION pg_buffercache_pages_wrap()
-RETURNS SETOF RECORD
-AS 'MODULE_PATHNAME', 'pg_buffercache_pages'
-LANGUAGE C;
-
 -- Create a view for convenient access.
 CREATE VIEW pg_buffercache AS
-	SELECT P.* FROM pg_buffercache_pages_wrap() AS P
-	(bufferid integer, relfilenode oid, reltablespace oid, reldatabase oid,
-	 relforknumber int2, relblocknumber int8, isdirty bool, usagecount int2);
+	SELECT * FROM pg_buffercache_pages();
 
 -- Don't want these to be available to public.
-REVOKE ALL ON FUNCTION pg_buffercache_pages_wrap() FROM PUBLIC;
 REVOKE ALL ON pg_buffercache FROM PUBLIC;

contrib/pg_buffercache/pg_buffercache--unpackaged--1.0.sql

@@ -3,5 +3,4 @@
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION pg_buffercache" to load this file. \quit
 
-ALTER EXTENSION pg_buffercache ADD function pg_buffercache_pages();
 ALTER EXTENSION pg_buffercache ADD view pg_buffercache;

contrib/pg_buffercache/pg_buffercache_pages.cpp

@@ -1,6 +1,6 @@
 /*-------------------------------------------------------------------------
  *
- * pg_buffercache_pages.c
+ * pg_buffercache_pages.c (deprecated in openGauss)
  *	  display some contents of the buffer cache
  *
  *	  contrib/pg_buffercache/pg_buffercache_pages.c