[mutter] Use _NO_CONTEXT when creating images for EGL_WAYLAND_BUFFER_WL

[Rui Matos <rtcm src gnome org>]

commit 7d9af9585d888291797e61ef0822240db5510999
Author: Sjoerd Simons <sjoerd simons collabora co uk>
Date:   Fri Apr 15 16:00:09 2016 +0200

    Use _NO_CONTEXT when creating images for EGL_WAYLAND_BUFFER_WL
    
    The WL_bind_wayland_display spec says that EGL images should be created
    using EGL_WAYLAND_BUFFER_WL as the target and a NULL context. Mesa
    seems to be lenient and accept any context, however some other stacks
    aren't so forgiving and fail if anything apart from EGL_NO_CONTEXT is
    used.
    
    Signed-off-by: Sjoerd Simons <sjoerd simons collabora co uk>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=769731

 cogl/cogl/winsys/cogl-winsys-egl.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/cogl/cogl/winsys/cogl-winsys-egl.c b/cogl/cogl/winsys/cogl-winsys-egl.c
index ab25bd1..36122f2 100644
--- a/cogl/cogl/winsys/cogl-winsys-egl.c
+++ b/cogl/cogl/winsys/cogl-winsys-egl.c
@@ -1029,6 +1029,13 @@ _cogl_egl_create_image (CoglContext *ctx,
     egl_ctx = EGL_NO_CONTEXT;
   else
 #endif
+#if COGL_HAS_WAYLAND_EGL_SERVER_SUPPORT
+  /* The WL_bind_wayland_display spec states that EGL_NO_CONTEXT is to be used
+   * in conjunction with the EGL_WAYLAND_BUFFER_WL target */
+  if (target == EGL_WAYLAND_BUFFER_WL)
+    egl_ctx = EGL_NO_CONTEXT;
+  else
+#endif
     egl_ctx = egl_display->egl_context;
 
   return egl_renderer->pf_eglCreateImage (egl_renderer->edpy,