Nearly a complete rewrite of elf.h.

Start with NetBSD's sys/arch/mips/include/elf_machdep.h 1.18. Remove the NetBSD
specific glue pieces (leaving mostly just relocation types).

Add in FreeBSD specific glue pieces from older versions of this file, and
move to the top of the file:
r237430 | kib | 2012-06-22 00:38:31 -0600 (Fri, 22 Jun 2012) | 5 lines
r232449 | jmallett | 2012-03-03 01:19:18 -0700 (Sat, 03 Mar 2012) | 18 lines
r217097 | kib | 2011-01-07 07:22:34 -0700 (Fri, 07 Jan 2011) | 3 lines
r211412 | kib | 2010-08-17 02:55:45 -0600 (Tue, 17 Aug 2010) | 7 lines
r202908 | gonzo | 2010-01-23 19:59:22 -0700 (Sat, 23 Jan 2010) | 4 lines
r195356 | imp | 2009-07-05 01:00:51 -0600 (Sun, 05 Jul 2009) | 6 lines
r195128 | gonzo | 2009-06-27 17:27:41 -0600 (Sat, 27 Jun 2009) | 4 lines
r197933 | kib | 2009-10-10 09:31:24 -0600 (Sat, 10 Oct 2009) | 9 lines
r189926 | kib | 2009-03-17 06:50:16 -0600 (Tue, 17 Mar 2009) | 9 lines
r186191 | imp | 2008-12-16 13:07:47 -0700 (Tue, 16 Dec 2008) | 7 lines
as closely as I can tell, the projects/mips branch merge was disruptive
to good history.

This should make merges easier in the future from NetBSD and vice versa.
Fix a bug where SCTP_ENABLE_STREAM_RESET is not handled by
sctp_opt_info().

MFC after: 3 days
Fix the handling of SCTP_CURRENT_ASSOC and SCTP_ALL_ASSOC in
sctp_opt_info().

MFC after: 3 days