Rename pending_list_cleanup_size to gin_pending_list_limit.

Since this parameter is only for GIN index, it's better to
add "gin" to the parameter name for easier understanding.

src/backend/access/common/reloptions.c

@@ -218,7 +218,7 @@ static relopt_int intRelOpts[] =
 	},
 	{
 		{
-			"pending_list_cleanup_size",
+			"gin_pending_list_limit",
 			"Maximum size of the pending list for this GIN index, in kilobytes.",
 			RELOPT_KIND_GIN
 		},

src/backend/access/gin/ginfast.c

@@ -26,7 +26,7 @@
 #include "utils/rel.h"
 
 /* GUC parameter */
-int			pending_list_cleanup_size = 0;
+int			gin_pending_list_limit = 0;
 
 #define GIN_PAGE_FREESIZE \
 	( BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - MAXALIGN(sizeof(GinPageOpaqueData)) )
@@ -426,7 +426,7 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
 	 * call it when it can do all the work in a single collection cycle. In
 	 * non-vacuum mode, it shouldn't require maintenance_work_mem, so fire it
 	 * while pending list is still small enough to fit into
-	 * pending_list_cleanup_size.
+	 * gin_pending_list_limit.
 	 *
 	 * ginInsertCleanup() should not be called inside our CRIT_SECTION.
 	 */

src/backend/access/gin/ginutil.c

@@ -526,7 +526,7 @@ ginoptions(PG_FUNCTION_ARGS)
 	int			numoptions;
 	static const relopt_parse_elt tab[] = {
 		{"fastupdate", RELOPT_TYPE_BOOL, offsetof(GinOptions, useFastUpdate)},
-		{"pending_list_cleanup_size", RELOPT_TYPE_INT, offsetof(GinOptions,
+		{"gin_pending_list_limit", RELOPT_TYPE_INT, offsetof(GinOptions,
 																pendingListCleanupSize)}
 	};
 

src/backend/utils/misc/guc.c

@@ -2543,12 +2543,12 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
-		{"pending_list_cleanup_size", PGC_USERSET, CLIENT_CONN_STATEMENT,
+		{"gin_pending_list_limit", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum size of the pending list for GIN index."),
 			 NULL,
 			GUC_UNIT_KB
 		},
-		&pending_list_cleanup_size,
+		&gin_pending_list_limit,
 		4096, 64, MAX_KILOBYTES,
 		NULL, NULL, NULL
 	},

src/backend/utils/misc/postgresql.conf.sample

@@ -519,7 +519,7 @@
 #bytea_output = 'hex'			# hex, escape
 #xmlbinary = 'base64'
 #xmloption = 'content'
-#pending_list_cleanup_size = 4MB
+#gin_pending_list_limit = 4MB
 
 # - Locale and Formatting -