[mutter] util: Export meta_set_syncing() symbol

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

commit df8074c63633ba9c7599de285b7ae8c5a739035e
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Mar 2 11:05:15 2021 +0100

    util: Export meta_set_syncing() symbol
    
    Will be set by MetaContextTest, until we can move away from the function
    completely.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1861>

 src/core/util-private.h | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/core/util-private.h b/src/core/util-private.h
index 010de58316..ff9d7ce426 100644
--- a/src/core/util-private.h
+++ b/src/core/util-private.h
@@ -36,7 +36,10 @@
 
 void     meta_set_verbose (gboolean setting);
 void     meta_set_debugging (gboolean setting);
+
+META_EXPORT_TEST
 void     meta_set_syncing (gboolean setting);
+
 void     meta_set_replace_current_wm (gboolean setting);
 void     meta_set_is_wayland_compositor (gboolean setting);