Add missing #include, to suppress compiler warning.

Author: robertmhaas

src/backend/storage/file/fd.c

@@ -53,6 +53,7 @@
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
+#include "pgstat.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
 #include "utils/guc.h"