qtqa: skip QtWebEngine's license check

QtWebEngine adopted some headers from webkit, which won't
pass the license check.

Change-Id: I97fae1646f814f7792ae2bcb97005c1e575c5748
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>