scripts/xldd: avoid reporting duplicates

Once a NEEDED dependency has been solved, do not report it
if other dependencies depend on it.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

reporter_name="Thomas Petazzoni"

reporter_url="http://www.free-electrons.com/"

reporter_comment="Very basic testing only"