Windows does not necessarily mean Cygwin, it could also be MSYS. The
latter ships with a version of "kill" that does not understand "-f".
In msysgit this was addressed by shipping Cygwin's version of kill.

Properly fix this by using the stock Windows "taskkill" command instead,
which is available since Windows XP Professional.
Signed-off-by: NSebastian Schuberth <sschuberth@gmail.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>