Disable QtWebKit features in build.sh.

This reduces the amount of patches we need to do within QtWebKit.
Update qtbase and qtwebkit to point at last rebase of current stable.
Update Qt5 submodules.
Restructure build script and error-out sooner when any dependency fails to build.
Merge branch 'kdab-qt5' into javabindings

Conflicts:
	build.sh
Also output Qt version string in phantomjs --version.
Merge branch 'kdab-qt5' into javabindings