We add libsdl into sato image since some 3D graphics testing needs it. (From OE-Core rev: 0934dc7c421ea6fb8f16ce535be72dda9ecb17de) Signed-off-by: Jiajun Xu <jiajun.xu@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>