*) Added "#include <string.>" to include/threads.h

  *) Added "#include <string.>" to include/threads.h
     It' wouldn't compile on OSX without this.

  *) Removed the mutex the vout and intf thread (were supposed to use)
     for syncronizing acces to the p_vout->p_sys structure.
     The p_vout->change_lock mutex is used for syncronization now. (and
     should make synronization work)