Qt3D had temporarily resided in the Qt5 repository under qtquick3d.
There is now a qt3d submodule which is compiling and testing correctly.
Qt5 had previously removed support for building the qtquick3d submodule
by default. This commit is the final step in cleaning up the previous
version.

Task-number: QTBUG-22098

Change-Id: I39fdbd7c58a0076c288d8c0570e892b5d0df4ff9
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
Reviewed-by: Danny Pope <daniel.pope@nokia.com>