[mutter] monitor-manager: Add back warning messages

[Marco Trevisan <marcotrevi src gnome org>]

commit d9c18fd5bbd6b06453bb06a64eb8b31866d2f963
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Apr 24 15:25:56 2018 +0200

    monitor-manager: Add back warning messages
    
    For some reason "backends: Remove X11 idle-monitor backend" removed
    unrelated warning messages for when generated monitor configurations
    that should work didn't, which also made the unit tests fail.
    
    This commit adds them back, which also makes the tests pass again.

 src/backends/meta-monitor-manager.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/backends/meta-monitor-manager.c b/src/backends/meta-monitor-manager.c
index 0b5e54c48..1d6690e45 100644
--- a/src/backends/meta-monitor-manager.c
+++ b/src/backends/meta-monitor-manager.c
@@ -585,6 +585,8 @@ meta_monitor_manager_ensure_configured (MetaMonitorManager *manager)
                                                        &error))
         {
           g_clear_object (&config);
+          g_warning ("Failed to use linear monitor configuration: %s",
+                     error->message);
           g_clear_error (&error);
         }
       else
@@ -602,6 +604,8 @@ meta_monitor_manager_ensure_configured (MetaMonitorManager *manager)
                                                        &error))
         {
           g_clear_object (&config);
+          g_warning ("Failed to use fallback monitor configuration: %s",
+                     error->message);
           g_clear_error (&error);
         }
       else