Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Merge from OpenBSD:
revision 1.13
date: 2015/12/09 11:54:12; author: tb; state: Exp; lines: +2 -2
Add a cast to silence a compiler warning by clang on FreeBSD.
From Craig Rodrigues.
ok tedu@

Merge from OpenBSD:
revision 1.12
date: 2015/12/05 13:06:52; author: claudio; state: Exp; lines: +4 -6
Do not loop on EAGAIN in imsg_read(). Better to return the error to the
caller and let him do another poll loop. This fixes spinning relayd
processes seen on busy TLS relays. OK benno@ henning@

Merge from OpenBSD:
revision 1.11
date: 2015/11/27 01:57:59; author: mmcc; state: Exp; lines: +2 -3
Remove three NULL-checks before free(). ok millert@

Import imsg from OpenBSD's libutil.

imsg provides functions for communication between processes
using sockets. imsg is used by programs in OpenBSD such as ypldap.