Set necessary default compiler flags for iOS Simulator builds.
Set necessary default compiler flags for iOS Simulator builds.

This is consistent with Xcode and also required for building 32-bit iOS
Simulator binaries that use ARC, since the compiler's default
Objective-C ABI version is 0 ("legacy" runtime) for 32-bit targets.

Change-Id: Ia7575fd9d4788170a6805a8ff8fe5f6426003da9
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@digia.com>

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