cmQtAutoGenInitializer::InitCustomTargets and
cmQtAutoGenInitializer::SetupCustomTargets
now return their success value which gets evaluated
and passed on by the caller (cmGlobalGenerator).

Checks for the existance of the moc/uic/rcc
binaries have been introduces in cmQtAutoGenInitializer.
Additionally they get called once with a "-h"
argument to determine if they're functional.
This way any binary-not-found problem is caught
during the configuration phase.