When DISTRO_FEATURES does not contain x11, disable GTK GUI and
also don't add gtk+ to the DEPENDS
(From OE-Core rev: 1b41a4660d0dd8f1863bb94d08562927cc108ee1)
Signed-off-by: Jack Mitchell <jack.mitchell@dbbroadcast.co.uk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>