Fix the build with recent qtbase

Since 3cd70c11bc7bbe3c5e9e4972d2273cf51bbdc30e in
qtbase Qt modules require cmake tests to be present
which makes QtWebEngine fail with "Missing CMake tests."
We do not support building with cmake at this point,
so disable these tests by setting CMAKE_MODULE_TESTS
to '-' for module pro files.

Change-Id: I777e6b2c7ce975ad021281800987f9d3ce173399
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>