BUG/MINOR: systemd: potential zombie processes

In systemd mode (-Ds), the master haproxy process is waiting for each
child to exit in a specific order. If a process die when it's not his
turn, it will become a zombie process until every processes exit.

The master is now waiting for any process to exit in any order.

This patch should be backported to 1.7, 1.6 and 1.5.
1 file changed