This allows libzypp to successfully build when x11 is not in
DISTRO_FEATURES (avoiding the libzypp -> libproxy -> gconf -> gtk+
dependency chain which without X results in gtk+ failing at
do_configure).
Fixes [YOCTO #2320].
(From OE-Core rev: 973351cf2e338f07c11395d494193e9c62857f2d)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>