[mutter] shaped-texture: Make setting the same texture a no-op

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 3969285e5cf1068c26775d3fcc9c2c95e61ac467
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Dec 6 18:39:56 2019 +0100

    shaped-texture: Make setting the same texture a no-op
    
    Will be helpful when pushing state to the shaped texture, letting the
    one pushing not have to care about checking if anything changed.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/961

 src/compositor/meta-shaped-texture.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/compositor/meta-shaped-texture.c b/src/compositor/meta-shaped-texture.c
index 2e3020d4e..49c91ff1c 100644
--- a/src/compositor/meta-shaped-texture.c
+++ b/src/compositor/meta-shaped-texture.c
@@ -944,6 +944,9 @@ meta_shaped_texture_set_texture (MetaShapedTexture *stex,
 {
   g_return_if_fail (META_IS_SHAPED_TEXTURE (stex));
 
+  if (stex->texture == texture)
+    return;
+
   set_cogl_texture (stex, texture);
 }