Install diffutils test suite and run it as ptest.
(From OE-Core rev: 14cc60db64975ad7cb8ae7d50e0233e9d59713df)
Signed-off-by: Chong Lu <Chong.Lu@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>