Run parse_query() in get_posts() so that the query vars are always parsed for...

Run parse_query() in get_posts() so that the query vars are always parsed for set(), get_posts() patterns. fixes #16545 for trunk

git-svn-id: https://core.svn.wordpress.org/trunk@17451 1a063a9b-81f0-0310-95a4-ce76da25c4cd