Create correct permalinks for child posts of hierarchical post types when default permalinks are used.

props loushou.
fixes #29615 for trunk.
Built from https://develop.svn.wordpress.org/trunk@29765


git-svn-id: http://core.svn.wordpress.org/trunk@29537 1a063a9b-81f0-0310-95a4-ce76da25c4cd