Fixing g_format_size_full() on Windows-x64

For some reasons, the buffer used in the Format struct was not long
enough on Windows-x64 and the final null ('\0') character was omitted
leading to a limited memory disclosure.

glib/gutils.c

@@ -2300,7 +2300,7 @@ g_format_size_full (guint64          size,
   struct Format
   {
     guint64 factor;
-    char string[9];
+    char string[10];
   };
 
   typedef enum