Automatically esc_url() the URL echoed by the_permalink().

This makes the_permalink() useful, rather than needing to do `echo esc_url( get_permalink() )` to get proper encoding of ampersands, etc. This will not double-encode when esc_url() has already been applied to the filter here, but that code can now be removed.

props mfields.
fixes #17562.



git-svn-id: http://core.svn.wordpress.org/trunk@23527 1a063a9b-81f0-0310-95a4-ce76da25c4cd