syslogd: Ignore signals in sigcatch[]

[jfree]

Summary

Instead of blocking signals in sigcatch[], just ignore them. This frees
up some space on the proc's sigqueue.

[markj]

There is some code elsewhere in syslogd.c which unblocks signals in a child process. Is it still correct?

[jfree]

• Set signal handler to SIG_DFL for signals in sigaction[] upon fork()
• Add comment explaining how syslogd handles child process reaping