Fix parsing in `wp_match_mime_types()` to allow some mime-types with `+` in them to appear in the list of filter links shown above the list table on `upload.php`.	

Props _duck.
Fixes #20672.



git-svn-id: https://develop.svn.wordpress.org/trunk@28553 602fd350-edb4-49c9-b593-d223f7449a82