qt5: upgrade git recipes to 5.4-beta1

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
qt5: update LICENSE in git recipes

* move common part to qt5-git.bb and add GPLv2 only
  in recipes which allow to use that
* for details about LGPLv3 read:
  http://blog.qt.digia.com/blog/2014/08/20/adding-lgpl-v3-to-qt/

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
qtbase: delete mkspecs/macx-ios-clang to hide QA issue

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

* now when it was moved from qt-labs to qt prefix we can reuse the
  SRC_URI from qt5-git.bb

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