explain what's going on, add another kludge for -g
whitespace cleanup
Back changes from 1.349 on since the -Wl,-x bug has been fixed in binutils.
execve_runproc: Reorder a few local vars.  Avoid reuse.  No functional changes.
execve_runproc: The stack address passed to the newly execve()'ed process,
via the 3rd register argument, always points to the stack base address (==
minsaddr (min stack address) + ssize (stack size)).  Clarify that.
recognize -V none
mention -V none
Fix up some KNF errors.
Reorder a new lines.  Comments.
execve_runproc: Unbreak __MACHINE_STACK_GROWS_UP machines.  Clarify the stack
address allocation code.  Summarize an awful big comment about the _rtld()
"gap".

(The log message in Rev. 1.384 was wrong; the new stack address is passed
not via the 3rd register argument, but via the SP.  The 3rd is for ps_strings.)
execve_runproc: Move a long code block handling credential into a separate
function.  No functional changes.
execve_runproc: Refactor debug code.
Don't #define DEBUG_EXEC.
Fix typo and unbreak the build for various arm kernel builds.
Trailing whitespace
revarprequest: Avoid leaking mbuf.

In revarprequest, an mbuf could perhaps be leaked in an error path.
My reading of the code is that this is not possible, because ar_pro is
set to ETHERNET_IP, and ar_tha can only be null in the 1394 case.
But, better to have the free call anyway; ar_tha does not have a
documented interface contract :-)

Pointed out by Maxime Villard.
Remove buggy linux completion API emulation and use the common version.
execve_runproc: Correct thinko in Rev. 1.386; the new SP always points to
after (higher adderss) argc/argv/env/aux/strings regardless of stack growing
direction .  Machines with grow-up stack will detect the top of
argc/argv/env/aux/strings by the address of *argv[] via ps_strings:ps_argvstr.

This means that old comments about RTLD_GAP are all obsolete.

With help from Nick Hudson.
KDASSERT -> KDASSERTMSG
NetBSD.org police.