[mutter] monitor-config-manager: Mark the mirroring logical monitor as primary

[Marge Bot <marge-bot src gnome org>]

commit 8698b4a493d00b79115ad655373803e5238e529c
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Jun 23 12:44:21 2022 +0200

    monitor-config-manager: Mark the mirroring logical monitor as primary
    
    The resulting logical monitor was eventually marked as primary anyway,
    but without the config being marked as such, various primary properties
    was not set e.g. the one on the MetaOutput. Also, tests would fail.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2479>

 src/backends/meta-monitor-config-manager.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/backends/meta-monitor-config-manager.c b/src/backends/meta-monitor-config-manager.c
index 84ea04faa8..f712e9c9a6 100644
--- a/src/backends/meta-monitor-config-manager.c
+++ b/src/backends/meta-monitor-config-manager.c
@@ -1275,7 +1275,8 @@ create_for_switch_config_all_mirror (MetaMonitorConfigManager *config_manager)
       .height = height
     },
     .scale = best_scale,
-    .monitor_configs = monitor_configs
+    .monitor_configs = monitor_configs,
+    .is_primary = TRUE,
   };
 
   logical_monitor_configs = g_list_append (NULL, logical_monitor_config);