Fix changes made in r249408.

In some cases, kern_envp is set by the architecture code and env_pos does
not contain the length of the static kernel environment. In these cases
r249408 causes the kernel to discard the environment.

Fix this by updating the check for empty static env to *kern_envp != '\0'

Reported by:	np@
MFprojects/camlock r248894:
Use full freeze while PMP does hard reset. This is only cosmetical change.
Fix the name of the pcb member in the comments.

Submitted by:	Oliver Pinter <oliver.pntr@gmail.com>
MFC after:	3 days
move the error report to a lower log level...  Now you can see when it
returns an error without getting every single io that went through it..

MFC after:	1 week
Fix undefined behaviour in several gpio_pin_setflags() routines (under
sys/arm and sys/mips), squelching the clang 3.3 warnings about this.

Noticed by:	tinderbox and many irate spectators
Submitted by:	Luiz Otavio O Souza <loos.br@gmail.com>
PR:		kern/177759
MFC after:	3 days
Create sysctl node 'hw.vmm.vmx' and populate it with oids that expose the VMX
hardware capabilities.

Obtained from:	NetApp
Clean up the ntop / pton code.  Part of a patch which has been submitted
upstream but not yet adopted.
Include ldns's b{32,64}_{ntop,pton}().
Fixes for build errors.  Certain macros require use to reference the result value.  FreeBSD 9.1 Release x86_64 on EC2.  Build command: CC=clang CXX=clang++ CPP=clang-cpp MAKEOBJDIRPREFIX=/mnt/freebsd-build make buildkernel KERNCONF=XENHVM