Ticket #2664: ogm extension was deprecated in favor of .ogv.

Conform to http://wiki.xiph.org/MIME_Types_and_File_Extensions, .ogm
extension was deprecated in favor of .ogv (with mimetype video/ogg).

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

misc/mc.ext.in

@@ -496,7 +496,7 @@ shell/i/.wmv
 regex/i/\.fl[icv]$
 	Include=video
 
-regex/i/\.og[mv]$
+shell/i/.ogv
 	Include=video
 
 regex/i/\.ra?m$