[mutter] logical-monitor: Don't set the CRTC logical monitor if not assigned

[Jonas Ådahl <jadahl src gnome org>]

commit 7967ceee98f7c741a099fc1617c57003bef87aac
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Mar 7 18:03:24 2017 +0800

    logical-monitor: Don't set the CRTC logical monitor if not assigned
    
    When adding a monitor and all its outputs, don't try to set the logical
    monitor of the outputs CRTC if none was assigned. This might happen if
    a tiled monitor only uses a subset of the connectors it are connected
    via.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779745

 src/backends/meta-logical-monitor.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/backends/meta-logical-monitor.c b/src/backends/meta-logical-monitor.c
index 44366b0..a3c5acc 100644
--- a/src/backends/meta-logical-monitor.c
+++ b/src/backends/meta-logical-monitor.c
@@ -95,7 +95,8 @@ meta_logical_monitor_add_monitor (MetaLogicalMonitor *logical_monitor,
           MetaOutput *output = l_output->data;
 
           is_presentation = is_presentation && output->is_presentation;
-          output->crtc->logical_monitor = logical_monitor;
+          if (output->crtc)
+            output->crtc->logical_monitor = logical_monitor;
         }
     }