of the recent WARNS commits. The idea is:
1) FreeBSD id tags should follow vendor tags.
2) Vendor tags should not be compiled (though copyrights probably should).
3) There should be no blank line between including cdefs and __FBSDIF.
Turned the shell script into a binary fixing several minor buglets.
Mention _POSIX_SOURCE feature test macro in man page.
PR: bin/19337
Submitted by: schweikh
Reviewed by: joerg, bde
MFC after: 2 weeks