Fix build on QNX
Fix build on QNX

There is std::isnan and friends, but math.h also defines isnan as macro,
so std::isnan expands to std::whateverthemacrois and that fails to build.
So include math.h early on, get rid of the macros and then we can continue
to use std::isnan throughout the code base safely.

Change-Id: Ifee580fa2adff396eb6d6f064d4c095a896fb022
Reviewed-by: Erik Verbruggen <5edfe905d082749f2ac3f4e6b42937f39f083771@digia.com>
Reviewed-by: Fabian Bumberger <e05aa9b88a4518509d2de3da94deb065ab9534a1@rim.com>

mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative