Don't leak a handle from _g_io_win32_get_module()

This call increments the DLL refcount by default and
needs a flag to avoid that.

gio/giomodule.c

@@ -1120,7 +1120,8 @@ void *
 _g_io_win32_get_module (void)
 {
   if (!gio_dll)
-    GetModuleHandleExA (GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
+    GetModuleHandleExA (GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
+                        GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
                         (const char *) _g_io_win32_get_module,
                         &gio_dll);
   return gio_dll;