Platform scope values not supported in Qt 4

There appears to be a bug in the qmake advanced usage documentation for platform scope values, the platform scope values are not supported in Qt4 (and are a feature of Qt5).

In addition to the win32, macx, and unix values used in many scope conditions, various other built-in platform and compiler-specific values can be tested with scopes. These are based on platform specifications provided in Qt's mkspecs directory.

Running the example code ( message($$QMAKESPEC ) using qmake from Qt4 will just output "Project MESSAGE:" with no actual output regardless if the mkspec is specified on the command line or otherwise.