Fix child restart by always calling close_sockets() when the child dies;

Fix child restart by always calling close_sockets() when the child dies;
otherwise open_sockets() fails, which causes start_child() to fail silently.

Furthermore, if open_sockets() fails and child_state is CH_DIED, it will
not be possible to start it manually later; therefore, set child_state
to CH_STOPPED when open_sockets() fails.

Note: it wouldn't hurt if open_sockets() were a little more talkative.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@1710 d4fa192b-c00b-0410-8231-f00ffab90ce4