Update P5Regex to have user-chosen stopper hook.
Update P5Regex to have user-chosen stopper hook.

Also means that a workaround can be eliminated.

cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp