Adds _cogl_wayland_texture_2d_new_from_buffer API

This adds internal API to be able to wrap a wayland buffer as a
CoglTexture2D. There is a --enable-wayland-egl-server option to decide
if Cogl should support this feature and potentially any EGL based winsys
could support this through the EGL_KHR_image_base and
EGL_WL_bind_display extensions.

cogl/cogl-display.c

@@ -129,3 +129,13 @@ cogl_gdl_display_set_plane (CoglDisplay *display,
 }
 #endif
 
+#ifdef COGL_HAS_WAYLAND_EGL_SERVER_SUPPORT
+void
+cogl_wayland_display_set_compositor_display (CoglDisplay *display,
+                                             struct wl_display *wayland_display)
+{
+  g_return_if_fail (display->setup == FALSE);
+
+  display->wayland_compositor_display = wayland_display;
+}
+#endif