This is a major cleanup of the LWKT message port code. The messaging code

This is a major cleanup of the LWKT message port code.  The messaging code
is getting closer to being directly useable by userland.  With these changes
message/port operations are now far better abstracted then they were before.

    * Stale fields have been removed from struct lwkt_msg.
    * lwkt_abortmsg() has been revamped to make it easier to support.
    * lwkt_waitmsg has been converted to a port function.
    * mp_*port() function fields have been renamed for better readability.
    * ms_cleanupmsg has been removed from struct lwkt_msg.
    * Union sysmsg is now struct sysmsg.
    * A copyout function has been added to struct sysmsg.
    * The system calls have been regenerated.