Fix an evil bug: when we failed to write to our log, fputs()

Fix an evil bug: when we failed to write to our log, fputs()
gave us a sigpipe, and we logged that we were ignoring it,
causing us to fail to log that, and delete the log entry. Then
when the signal handler exited, we proceeded to delete the log
entry that had already been deleted.

Now we make sure to only log inside our signal handler if we'll
be exit()ing right after.

svn:r2388