by W.Richard Ste vens. EINTR handling suggested by bde@freebsd.org).
Code cleanup:
1. Add missing return type.
2. Replace 'union wait' by int.
3. Use Posix-style signal handling instead of signal().
4. Use fork() instead of deprecated vfork().
5. Block signals before fork()'ing, instead of after.
6. Return -1 if fork() fails, instead of 0.
7. Add EINTR handling for waitpid() call.
Also add claim of Posix conformance to man page.
in the main text of various man pages.
Thanks to Warner Losh for adding an option to manck to allow
it to scan the entire man page looking for bogus xrefs, instead
of just checking the SEE ALSO section.
