XML-RPC: Explicitly unset the reference to the parser resource after calling xml_parser_free() to avoid memory leaks in PHP 7.0.0 or higher.

Props procifer, ayeshrajans.
Fixes #49700.
Built from https://develop.svn.wordpress.org/trunk@48322


git-svn-id: http://core.svn.wordpress.org/trunk@48091 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rss.php

@@ -94,6 +94,7 @@ class MagpieRSS {
 		}
 
 		xml_parser_free( $this->parser );
+		unset( $this->parser );
 
 		$this->normalize();
 	}