[mutter] monitor-config: prevent assert that at least one output is connected

[Giovanni Campagna <gcampagna src gnome org>]

commit 809dbe16d6ca7b7ea8ef69f9cff9d763cc5ff986
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Tue Oct 15 20:12:05 2013 +0200

    monitor-config: prevent assert that at least one output is connected
    
    Apparently some connector technologies don't distinguish between
    on and off, and there might be valid use cases for running without
    any connected monitor.
    In that case, just avoid any configuration at all.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=709009

 src/core/monitor-config.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/src/core/monitor-config.c b/src/core/monitor-config.c
index 8fcd496..82ea0b1 100644
--- a/src/core/monitor-config.c
+++ b/src/core/monitor-config.c
@@ -824,6 +824,9 @@ meta_monitor_config_get_stored (MetaMonitorConfig *self,
   MetaConfiguration key;
   MetaConfiguration *stored;
 
+  if (n_outputs == 0)
+    return NULL;
+
   make_config_key (&key, outputs, n_outputs, -1);
   stored = g_hash_table_lookup (self->configs, &key);
 
@@ -1231,6 +1234,12 @@ meta_monitor_config_make_default (MetaMonitorConfig  *self,
   outputs = meta_monitor_manager_get_outputs (manager, &n_outputs);
   meta_monitor_manager_get_screen_limits (manager, &max_width, &max_height);
 
+  if (n_outputs == 0)
+    {
+      meta_verbose ("No output connected, not applying configuration\n");
+      return;
+    }
+
   default_config = make_default_config (self, outputs, n_outputs, max_width, max_height);
 
   if (default_config != NULL)