gutils: Do not translate OS names

The code is intended to provide an interface similar to /etc/os-release,
but /etc/os-release isn't designed to be translated.

glib/gutils.c

@@ -1373,7 +1373,7 @@ g_get_os_info (const gchar *key_name)
 {
 #if defined (__APPLE__)
   if (g_strcmp0 (key_name, G_OS_INFO_KEY_NAME) == 0)
-    return g_strdup (_("macOS"));
+    return g_strdup ("macOS");
   else
     return NULL;
 #elif defined (G_OS_UNIX)