Mark validate_email() with _deprecated_function(). Props ShaneF. fixes #11745

git-svn-id: https://develop.svn.wordpress.org/trunk@12868 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/ms-deprecated.php

@@ -129,6 +129,7 @@ function is_main_blog() {
  * @deprecated 3.0
  */
 function validate_email( $email, $check_domain = true) {
+	_deprecated_function( __FUNCTION__, '3.0', 'is_email()' );
 	return is_email( $email, $check_domain );
 }