Upgrade from version 5.0.67 to 5.0.67nb1.

Two changes to the rc.d script:
1) Move the setting of pidfile to a place so that setting mysqld_datadir
    in rc.conf will actually work; otherwise, if you use a non-default
    mysqld_datadir, mysqld will not start.
2) ad@ pointed me to http://bugs.mysql.com/bug.php?id=18526, and said
    that --skip-thread-priority should not be used on NetBSD, and the
    PR spoke about Darwin / OS/X.  I'm guessing that this might work
    if the host platform is Linux or SunOS (the latter is unconfirmed).
    So add that option to the startup in all other cases.

(he)