cancel the timeout upon disabling profiling / virtual timer;  so that the timeout doesn't happen if setitimer is called between the profiling / virtual timer expires and the timeout is scheduled. firefox triggered this Profiling timer expired problem when in uthread execve signal was being delivered after timer has already been disabled;  as reported on ports@ recently. special thanks to kettenis@, kurt@, guenther@. agreed by kettenis@, tedu@.  ok guenther@. reminded & ok fgs@.  tested by ian@.
cancel the timeout upon disabling profiling / virtual timer;  so
that the timeout doesn't happen if setitimer is called between the
profiling / virtual timer expires and the timeout is scheduled.
firefox triggered this Profiling timer expired problem when in
uthread execve signal was being delivered after timer has already
been disabled;  as reported on ports@ recently.
special thanks to kettenis@, kurt@, guenther@.
agreed by kettenis@, tedu@.  ok guenther@.
reminded & ok fgs@.  tested by ian@.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars