Don't deploy system D3D compilers on Windows Phone and
introduce option to turn it off.

Deploy d3dcompiler_qt for Qt versions >= 5.3 should it exist.

Add code to determine the Qt version number (for which qmake does
not write a newline character).

Task-number: QTBUG-35597

Change-Id: Ic42954959b447d8fe0bd0adff064df6711992529
Reviewed-by: Andrew Knight <andrew.knight@digia.com>