qt5webkit: restore package

qt5webkit: restore package

Although this package has been removed from the official release
packages since Qt5.6.0, it is still available for users to build
it from source. This is useful for platforms without GPU since its
successor (QtWebEngine) requires OpenGL support.

The package now matches the community-based meta-qt5 Yocto layer,
using the exact same revision of the qtwebkit source from github:
https://github.com/meta-qt5/meta-qt5/commit/e434995a

Here is the project source tree:
https://github.com/qtproject/qtwebkit

All the patches have been pulled from Yocto as well.

Since we are now using the source from the git repository, we need
to create an empty .git/ folder to force the headers re-generation.
https://github.com/meta-qt5/meta-qt5/blob/jethro/recipes-qt/qt5/qt5.inc#L33

Note that GPLv3 license option has been added with this release.

Reviewed-by: Julien Corjon <corjon.j@ecagroup.com>
Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
[Thomas: fix license to be LGPLv2.1+, not LGPLv2+.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>