[mutter] backend-x11: Fallback to a default keymap if getting it from X fails

[Rui Matos <rtcm src gnome org>]

commit 9abc0712836c9e56ed08796645874cc0d10b1826
Author: Rui Matos <tiagomatos gmail com>
Date:   Mon Sep 21 17:25:40 2015 +0200

    backend-x11: Fallback to a default keymap if getting it from X fails
    
    This shouldn't fail but apparently sometimes it does and in that case
    having a possibly wrong idea of the keymap is still better than
    crashing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754979

 src/backends/x11/meta-backend-x11.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/x11/meta-backend-x11.c b/src/backends/x11/meta-backend-x11.c
index 7ad28fd..dbcd13f 100644
--- a/src/backends/x11/meta-backend-x11.c
+++ b/src/backends/x11/meta-backend-x11.c
@@ -760,6 +760,9 @@ meta_backend_x11_get_keymap (MetaBackend *backend)
                                                      priv->xcb,
                                                      xkb_x11_get_core_keyboard_device_id (priv->xcb),
                                                      XKB_KEYMAP_COMPILE_NO_FLAGS);
+      if (priv->keymap == NULL)
+        priv->keymap = xkb_keymap_new_from_names (context, NULL, XKB_KEYMAP_COMPILE_NO_FLAGS);
+
       xkb_context_unref (context);
     }