* msg_mime.c: explicit cast when assigning to mp_len
  Ignore-this: ca5b8291eb84d8b166ab7f659bcf69f8



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@12749 d0543943-73ff-0310-b7d9-9358b9ac24b2