Detect QMetaType::QReal from the definition of qreal

Detect QMetaType::QReal from the definition of qreal

Instead of relying to complex preprocessor expression that need to be
maintained to be kept the same as in qglobal.h

This aslo fix the case where QT_COORD_TYPE is defined (It is meant to be
defined to float or double, any other type would not make sense)

So now there should hopefully be only one place to change if one need to
adjust the type of qreal

Change-Id: I778312112603173562dbe675ab491b53d6cd2174
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>