Fix a typo.

MFC after:	3 days
Fix elfdump(1) usage in the userland CTF tests.

PR:		193110
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
Fix some incorrect endianness checks.

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
Use a devd event to start hv_kvpd instead of doing so in rc.d script.
This is cleaner and eliminates the unneeded startup of KVP daemon on
systems that do not run as a Hyper-V guest.

Submitted by:	hrs
X-MFC-with:	271493, 271688, 271699
Fix the stack tracing for dtrace/powerpc.

Summary:
Fix the stack tracing for dtrace/powerpc by using the trapexit/asttrapexit
return address sentinels instead of checking within the kernel address space.

As part of this, I had to add new inline functions.  FBT traces the kernel, so
we have to have special case handling for this, since a trap will create a full
new trap frame, and there's no way to pass around the 'real' stack.  I handle
this by special-casing 'aframes == 0' with the trap frame.  If aframes counts
out to the trap frame, then assume we're looking for the full kernel trap frame,
so switch to the real stack pointer.

Test Plan: Tested on powerpc64

Reviewers: rpaulo, markj, nwhitehorn

Reviewed By: markj, nwhitehorn

Differential Revision: https://reviews.freebsd.org/D788

MFC after:	3 week
Relnotes:	Yes
Fix a number of typos and programming errors in the userland CTF tests. It
seems that they would only pass by chance on illumos; on FreeBSD, they still
fail since userland CTF is not yet supported.

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division