cpp module: fix detection of ARMv8 (32-bit) architecture
cpp module: fix detection of ARMv8 (32-bit) architecture

qbs.architecture is now set to "armv8" instead of "arm" for this
architecture.

Change-Id: I6d33e9c34ae8e617d6d194981f6051b3a09f643a
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@qt.io>

qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs