[mutter] backends/x11: Improve grab-device clock updates

[Marco Trevisan <marcotrevi src gnome org>]

commit 1bfa20929b36d06cc23667d1122175149615b56d
Author: Jeff Smith <whydoubt gmail com>
Date:   Fri Jul 20 00:41:43 2018 -0500

    backends/x11: Improve grab-device clock updates
    
    meta_backend_x11_grab_device is performing X server clock comparison
    using the MAX macro, which comes down to a simple greater-than.
    
    Use XSERVER_TIME_IS_BEFORE, which is a better macro for X server
    clock comparisons, as it accounts for 32-bit wrap-around.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/174

 src/backends/x11/meta-backend-x11.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/x11/meta-backend-x11.c b/src/backends/x11/meta-backend-x11.c
index 9a1f35e6e..ed81364e2 100644
--- a/src/backends/x11/meta-backend-x11.c
+++ b/src/backends/x11/meta-backend-x11.c
@@ -547,8 +547,9 @@ meta_backend_x11_grab_device (MetaBackend *backend,
   XIEventMask mask = { XIAllMasterDevices, sizeof (mask_bits), mask_bits };
   int ret;
 
-  if (timestamp != META_CURRENT_TIME)
-    timestamp = MAX (timestamp, priv->latest_evtime);
+  if (timestamp != META_CURRENT_TIME &&
+      XSERVER_TIME_IS_BEFORE (timestamp, priv->latest_evtime))
+    timestamp = priv->latest_evtime;
 
   XISetMask (mask.mask, XI_ButtonPress);
   XISetMask (mask.mask, XI_ButtonRelease);