windows(JRUBY-4317):Process.kill raises an ArgumentError for unknown signals
windows(hangs):Process.kill signals the process group if the PID is zero
windows(hangs):Process.kill signals the process group if the signal number is negative
windows(hangs):Process.kill signals the process group if the short signal name starts with a minus sign
windows(hangs):Process.kill signals the process group if the full signal name starts with a minus sign
unstable(travis,intermittent):Process.kill accepts a signal name without the 'SIG' prefix
