MFC: r289878

timeout(1): fix the acceptable range values for parse_signal()

Before both 0 and sys_nsig would be successfully returned by parse_signal()
although being invalid signal numbers.

Submitted by: Alexandre Perrin <alex@kaworu.ch>

MFC: r268745,r268746,r268747,r268748,r268749,r268861,r268750,r268751,r268763
r273769,r273771,r276771,r278810

New BSDL timeout(1) utility compatible with GNU timeout

Relnotes: yes

MFC: r268745,r268746,r268747,r268748,r268749,r268861,r268750,r268751,r268763
r273769,r273771,r276771,r278810

New BSDL timeout(1) utility compatible with GNU timeout

Relnotes: yes