[mutter] cogl/texture-2d-gl: Try to determine format for external textures

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

commit b329256113e9af9edf148742b70b169f6b29bff0
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Dec 19 10:08:05 2018 +0100

    cogl/texture-2d-gl: Try to determine format for external textures
    
    Don't just set the internal format to the dummy format "any", as that causes
    code intended to be unreachable code to be reached. It's not possible to
    actually know the internal format of an external texture, however, so it might
    not actually correspond to the real format.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/362

 cogl/cogl/driver/gl/cogl-texture-2d-gl.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/cogl/cogl/driver/gl/cogl-texture-2d-gl.c b/cogl/cogl/driver/gl/cogl-texture-2d-gl.c
index ba90998ba..ec9ed9e18 100644
--- a/cogl/cogl/driver/gl/cogl-texture-2d-gl.c
+++ b/cogl/cogl/driver/gl/cogl-texture-2d-gl.c
@@ -470,7 +470,12 @@ allocate_custom_egl_image_external (CoglTexture2D *tex_2d,
 {
   CoglTexture *tex = COGL_TEXTURE (tex_2d);
   CoglContext *ctx = tex->context;
-  CoglPixelFormat internal_format = loader->src.egl_image_external.format;
+  CoglPixelFormat external_format;
+  CoglPixelFormat internal_format;
+
+  external_format = loader->src.egl_image_external.format;
+  internal_format = _cogl_texture_determine_internal_format (tex,
+                                                             external_format);
 
   _cogl_gl_util_clear_gl_errors (ctx);