syscallWatcher should support early cancellation

[jterry75]

The syscallWatcher today will effectively stack goroutines overtime. At the time of this post the defaultTimeout is 4 minutes which means that all syscalls (even completed ones) will have an open goroutine (although sleeping) for 4 minutes. This pattern should support a context.Context cancellation after a return from a syscall as we no longer need to monitor for a hung state.

It would likely look something like:

ctx, cancel := context.WithTimeout(context.Background(), defautTimeout)
defer cancel()
go syscallWatcher(ctx, ...)
// make syscall
return result

So if the syscall returns we cancel the syscallWatcher and if it times out before returning we get the appropriate syscall hung state as expected.

[jterry75]

This was fixed.