utilities » multiwatch

This patch adds a persistence option and special SIGHUP handling. This means that I can use spawn-fcgi and multiwatch with web app servers still under development, which are likely to be buggy and may not start.

Rather than multiwatch just giving up and exiting (which is awkward
because I start it using spawn-cfgi setuid option) the web app developers can debug their apps and then simply send multiwatch a SIGHUP, like so:
$ kill -HUP $( < /var/run/spawn-fcgi/whatever.pid )

The patch also makes multiwatch more generally useful by removing special handling for SIGUSR1. This change means that if children do gracefully exit on SIGUSR1 then multiwatch will also exit (assuming no --persist option) which should preserve existing behavior. (I hope this is not too controversial as in general SIGUSR1 does not mean process termination; there are other signals for that.)