Disable recursion for the process spinlock.

Tested by:	pho
Discussed with:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 month
Build infrastructure for elftoolchain tools

Set WITH_ELFTOOLCHAIN_TOOLS in src.conf to use the elftoolchain version
of the following tools:

 * addr2line
 * elfcopy (strip / mcs)
 * nm
 * size
 * strings

Reviewed by:	bapt (earlier version)
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D1224
Document ISP 2532 support and hint.isp.0.vports tunable.

MFC after:	1 week
Allow multiple devices to mmap.  It's impossible to prevent this with
checks on the open/close functions.

MFC after:	1 week
Fix inverted logic introduced in r272154.

Noticed by:	trasz
MFC after:	2 weeks
Pull in the NetBSD global offset table handling code. Clang 3.5 creates
relocations the linker complains about.

Obtained from:	NetBSD
MFC after:	1 Week
Set the correct architecture when targeting ARMv7

MFC after:	1 Week
Sponsored by:	ABT Systems Ltd
Use the floating-point instruction on ARMv7 as the clang 3.5 integrated
assembler doesn't allow these two instructions to use co-processor 11.

MFC after:	1 Week
Sponsored by:	ABT Systems Ltd
Make this work with pkgng, and allow PORTS_OPTS to be passed in