Use alternate JTHREAD_SETJMP() based on JTHREAD_JBLEN or JTHREAD_USE_SIGSETJMP defined in config.frag.  Default to setjmp().
Use alternate JTHREAD_SETJMP() based on JTHREAD_JBLEN or
JTHREAD_USE_SIGSETJMP defined in config.frag.  Default to setjmp().

kaffe/kaffe,kaffe/kaffe,kaffe/kaffe,kaffe/kaffe,kaffe/kaffe