ecore: drop libxputil from DEPENDS

* it was removed from oe-core
  http://git.openembedded.org/openembedded-core/commit/?id=5b3748d463a6666c0d8e2624092619da8d8e6328


* it needs to be explicitly disabled now, because recipe was removed in
  oe-core, but files still stay in sysroot and we cannot even
  cleansstate it now without recipes around.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>