As with the Python test, this can be both better and faster. No need to copy a
file, just run a one-liner.
(From OE-Core rev: c6eef46747fe58bb2310be4f06d2fa9b67901d72)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>