[mutter] clutter-stage-cogl: Fix uninitialized variable `use_clipped_redraw`

[Jonas Ådahl <jadahl src gnome org>]

commit f511f94aa29d9e265962b3dc7cbaeb392f63a1f8
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Fri Jun 19 15:34:59 2020 +0800

    clutter-stage-cogl: Fix uninitialized variable `use_clipped_redraw`
    
    I noticed my system would fall back to the slow unclipped (and
    uncullable) paint path whenever a window touched the left edge of
    the screen. Turns out that was a red herring. Just that
    `use_clipped_redraw` was uninitialized so clipping/culling was used
    randomly.
    
    So the compiler failed to notice `use_clipped_redraw` was uninitialized.
    Weirdly, as soon as you fix that it starts complaining that `buffer_age`
    might be uninitialized, which appears to be wrong. So we initialize that
    too, to shut up the compiler warnings/errors.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1323

 clutter/clutter/cogl/clutter-stage-cogl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/clutter/clutter/cogl/clutter-stage-cogl.c b/clutter/clutter/cogl/clutter-stage-cogl.c
index db87e39337..f7f71e6e16 100644
--- a/clutter/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/clutter/cogl/clutter-stage-cogl.c
@@ -551,7 +551,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   CoglFramebuffer *onscreen = clutter_stage_view_get_onscreen (view);
   cairo_rectangle_int_t view_rect;
   gboolean is_full_redraw;
-  gboolean use_clipped_redraw;
+  gboolean use_clipped_redraw = TRUE;
   gboolean can_blit_sub_buffer;
   gboolean has_buffer_age;
   gboolean swap_with_damage;
@@ -561,7 +561,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   cairo_region_t *swap_region;
   float fb_scale;
   int fb_width, fb_height;
-  int buffer_age;
+  int buffer_age = 0;
   gboolean res;
 
   clutter_stage_view_get_layout (view, &view_rect);