kill for PID -1 restored

kill for PID -1 restored

Both the man page and the shell builtin kill mention you can
use PID -1, which means nuke everything you can get at.
Alas this "fun" option was missing and the only way to get
around it was with "kill -HUP -- -1".

This small change means kill -HUP -1 is back for all those
destructive types. The error was introduced when the argument
parser was fixed for other problems.

Thanks to Mike for pointing this out.

Signed-off-by: Craig Small <csmall@enc.com.au>