bugfix: When we free the pixmap, clear any user data set on the resource

This was a cause of some memleaks/crashes in the wayland compositor
because the compositor was trying to access properties of the E_Pixmap
after it had already been freed. By setting the user_data to NULL, the
functions in the compositor which were failing will now stop trying to
access the pixmap after it's been freed.

Signed-off-by: Chris Michael <cp.michael@samsung.com>

src/bin/e_pixmap.c

@@ -97,7 +97,7 @@ _e_pixmap_free(E_Pixmap *cp)
         break;
       case E_PIXMAP_TYPE_WL:
 #if defined(HAVE_WAYLAND_CLIENTS) || defined(HAVE_WAYLAND_ONLY)
-        /* NB: No-Op. Nothing to free. image data no longer memcpy'd */
+        if (cp->resource) wl_resource_set_user_data(cp->resource, NULL);
 #endif
         break;
       default: