devtool: add basic means of running runqemu within the extensible SDK
We ship the runqemu script and if we build QEMU itself within the
extensible SDK, then it would be nice to be able to run it. This is a
very thin wrapper around runqemu, supplying the machine and image name
so the user doesn't need to. (This subcommand is only available within
the extensible SDK since it only really makes sense there where it is
otherwise hard to run runqemu directly.)
Implements [YOCTO #6657].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
