Doc: add Qt4 compatibility macros
Doc: add Qt4 compatibility macros

Task-number: QBS-210

Change-Id: Id1102281c495291b3226a797233e2e57fdf26d91
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@digia.com>

qt-labs/qbs,villytiger/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,villytiger/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,villytiger/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,villytiger/qbs,Distrotech/qbs,Distrotech/qbs,qt-labs/qbs,Distrotech/qbs,Distrotech/qbs,qt-labs/qbs,qt-labs/qbs,Distrotech/qbs,gatzka/qt-labs-qbs