Fix stale processes not being terminated by the rc(8) script.

Previously, when fcgiwrap_flags="-c [n]" with n > 1, only the controlling
process was terminated, with the children running. This patch fixes this
behaviour, terminating the children.

PR: 217297
Submitted by: lstewart
Reported by: spry anarchy in the ph
MFH: 2017Q2