[mutter] clutter/frame-clock: Fix dispatch lateness trace text

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

commit 7972594d267ef96d182908a21d090d842a400479
Author: Ivan Molodetskikh <yalterz gmail com>
Date:   Fri Sep 16 21:29:28 2022 -0700

    clutter/frame-clock: Fix dispatch lateness trace text
    
    It was unfortunately broken by a variable overwrite in
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2161.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2630>

 clutter/clutter/clutter-frame-clock.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/clutter/clutter/clutter-frame-clock.c b/clutter/clutter/clutter-frame-clock.c
index b223b85452..4d441c364b 100644
--- a/clutter/clutter/clutter-frame-clock.c
+++ b/clutter/clutter/clutter-frame-clock.c
@@ -664,10 +664,12 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
 
 #ifdef COGL_HAS_TRACING
   int64_t this_dispatch_ready_time_us;
+  int64_t this_dispatch_time_us;
 
   COGL_TRACE_BEGIN_SCOPED (ClutterFrameClockDispatch, "Frame Clock (dispatch)");
 
   this_dispatch_ready_time_us = g_source_get_ready_time (frame_clock->source);
+  this_dispatch_time_us = time_us;
 #endif
 
   ideal_dispatch_time_us = (frame_clock->last_dispatch_time_us -
@@ -737,7 +739,7 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
     {
       g_autofree char *description = NULL;
       description = g_strdup_printf ("dispatched %ld µs late",
-                                     time_us - this_dispatch_ready_time_us);
+                                     this_dispatch_time_us - this_dispatch_ready_time_us);
       COGL_TRACE_DESCRIBE (ClutterFrameClockDispatch, description);
     }
 #endif