Useful if one wants to separate stdout and stderr.
(From OE-Core rev: de9744c91a997a5ab0e7a19dbe13d8def8d62800)
Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>