tests/unix: Don't error immediately on timeout

tests/unix: Don't error immediately on timeout

On a heavily loaded system, it's possible that both our normal
condition *and* the timeout occurred.  In that case we can just ignore
the timeout.

While I did add a "sig_timeout" boolean, we don't need to add any
assertions around whether or not it was reached - the assertions
covering the non-timeout case are sufficient.  The sig_timeout boolean
is mainly for later debugging.

https://bugzilla.gnome.org/show_bug.cgi?id=700460