Fix aqo.fs_max_items, add.fss_max_items.

Set GucContext as PGC_POSTMASTER to allow values to be changed
only before the instance is started.

Author: Alena Rybakina

aqo.c

@@ -257,7 +257,7 @@ _PG_init(void)
 							&fs_max_items,
 							10000,
 							1, INT_MAX,
-							PGC_SUSET,
+							PGC_POSTMASTER,
 							0,
 							NULL,
 							NULL,
@@ -270,7 +270,7 @@ _PG_init(void)
 							&fss_max_items,
 							100000,
 							0, INT_MAX,
-							PGC_SUSET,
+							PGC_POSTMASTER,
 							0,
 							NULL,
 							NULL,