[mutter] region-utils: Make transform util const correct

[verdre <jonasd src gnome org>]

commit 03c65b93e68efa956bb2458b4e9fe66132e20eba
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue May 5 19:08:03 2020 +0200

    region-utils: Make transform util const correct
    
    The input should be const, as it will not be altered.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1237

 src/compositor/region-utils.c | 2 +-
 src/compositor/region-utils.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/compositor/region-utils.c b/src/compositor/region-utils.c
index 081f8a9063..4f5a2346a4 100644
--- a/src/compositor/region-utils.c
+++ b/src/compositor/region-utils.c
@@ -376,7 +376,7 @@ meta_make_border_region (cairo_region_t *region,
 }
 
 cairo_region_t *
-meta_region_transform (cairo_region_t       *region,
+meta_region_transform (const cairo_region_t *region,
                        MetaMonitorTransform  transform,
                        int                   width,
                        int                   height)
diff --git a/src/compositor/region-utils.h b/src/compositor/region-utils.h
index 745021b5be..298c5540e3 100644
--- a/src/compositor/region-utils.h
+++ b/src/compositor/region-utils.h
@@ -106,7 +106,7 @@ cairo_region_t * meta_make_border_region (cairo_region_t *region,
                                           int             y_amount,
                                           gboolean        flip);
 
-cairo_region_t * meta_region_transform (cairo_region_t       *region,
+cairo_region_t * meta_region_transform (const cairo_region_t *region,
                                         MetaMonitorTransform  transform,
                                         int                   width,
                                         int                   height);