Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

add DTrace systrace support for linux32 and freebsd32 on amd64 syscalls

This commits makes necessary changes in syscall/sysent generation
infrastructure.

PR: kern/152822
Submitted by: Artem Belevich <fbsdlist@src.cx>
Reviewed by: jhb (ealier version)
MFC after: 3 weeks

- Remove unused sysvec variables from various syscalls.conf.
- Send the systrace_args files for all the compat ABIs to /dev/null for
now. Right now makesyscalls.sh generates a file with a hardcoded
function name, so it wouldn't work for any of the ABIs anyway. Probably
the function name should be configurable via a 'systracename' variable
and the functions should be stored in a function pointer in the sysvec
structure.

GC unused 'syshide' override to /dev/null. This was here to disable
the output of the namespc column. Its functionality was removed some time
ago, but the overrides and the namespc column remained.

Begin attempting to consolidate the two different i386 emulations
on ia64 and amd64. I'm attempting to keep the generic 32bit-on-64bit
binary support seperate from the i386 support and the MD backend support.

Make this compile with WITNESS enabled. It wants the syscall names.

Initial support for executing IA-32 binaries. This will not compile
without a few patches for the rest of the kernel to allow the image
activator to override exec_copyout_strings and setregs.

None of the syscall argument translation has been done. Possibly, this
translation layer can be shared with any platform that wants to support
running ILP32 binaries on an LP64 host (e.g. sparc32 binaries?)