qt5: add qt5-module.bbclass

Upstream does not yet have the qt5-module.bbclass, until the change
gets merged, add our own bbclass.

Change-Id: Iea906d38a23024467a769210667fc32f4375419f
Reviewed-by: Teemu Holappa <teemu.holappa@theqtcompany.com>

classes/qt5-module.bbclass

+require recipes-qt/qt5/qt5.inc