Customize: Move the WordPress logo with a white background to the wp-includes directory.

This ensures that the image used as a default site icon looks good on a dark background.

The image was previously changed in the `wp-admin` directory, but the site icon is now loaded from `wp-includes`.

Follow-up to [36635], [47018], [47564], [47832].

Props ocean90.
Fixes #49798.

git-svn-id: https://develop.svn.wordpress.org/trunk@47838 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/functions.php

@@ -1668,7 +1668,7 @@ function do_favicon() {
 	 */
 	do_action( 'do_faviconico' );
 
-	wp_redirect( get_site_icon_url( 32, includes_url( 'images/w-logo-blue.png' ) ) );
+	wp_redirect( get_site_icon_url( 32, includes_url( 'images/w-logo-blue-white-bg.png' ) ) );
 	exit;
 }