Do not give a fatal error if attempting to compile ActiveQt on Unix
Do not give a fatal error if attempting to compile ActiveQt on Unix

Gracefully disable, instead of giving fatal error, if attempting to
compile ActiveQt on platforms where it is not supported.

This is helpful for the sake of having a uniform test procedure.
Without this, any test procedure needs to encode the logic that it
shouldn't attempt to compile ActiveQt on platforms other than Windows.
It is cleaner if the ActiveQt project itself gracefully degrades to
"do nothing" on those platforms where it is not supported.

Reviewed-by: Jason McDonald
Change-Id: Id2544b4cbba604a5f76ba56a12bb801cb36e1646

kobolabs/qtactiveqt,xsens/qtactiveqt,xsens/qtactiveqt,kobolabs/qtactiveqt