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.


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git-svn-id: http://core.svn.wordpress.org/trunk@28379 1a063a9b-81f0-0310-95a4-ce76da25c4cd