[mutter] legacy-monitor-config: Init is_underscanning config field from output

[Jonas Ådahl <jadahl src gnome org>]

commit 097ca01411695aa4f45cb1e13bab2c053c2dab5c
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Jan 17 11:22:48 2017 +0800

    legacy-monitor-config: Init is_underscanning config field from output
    
    Don't loose the is_underscanning field when creating a new configuration.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777732

 src/backends/meta-monitor-config.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor-config.c b/src/backends/meta-monitor-config.c
index 669a44c..ced2336 100644
--- a/src/backends/meta-monitor-config.c
+++ b/src/backends/meta-monitor-config.c
@@ -1119,6 +1119,7 @@ init_config_from_preferred_mode (MetaOutputConfig *config,
   config->transform = META_MONITOR_TRANSFORM_NORMAL;
   config->is_primary = FALSE;
   config->is_presentation = FALSE;
+  config->is_underscanning = output->is_underscanning;
 }
 
 /* This function handles configuring the outputs when the driver provides a