Fix typo in _deprecated_argument() and start using _deprecated_argument() in wp-includes files. See #11386 props nacin.

git-svn-id: https://develop.svn.wordpress.org/trunk@12537 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/post-template.php

@@ -246,6 +246,9 @@ function the_excerpt() {
  * @return string
  */
 function get_the_excerpt($deprecated = '') {
+	if ( !empty( $deprecated ) )
+		_deprecated_argument(__FUNCTION__, 'deprecated', '2.3');
+
 	global $post;
 	$output = $post->post_excerpt;
 	if ( post_password_required($post) ) {