qbs_benchmarker: Validate commit parameters
qbs_benchmarker: Validate commit parameters

It's possible to copy&paste old commit instead of a new one and easy to
overlook that mistake.

Change-Id: I408f256ba6b2f419b7cf90b7ed9ee582f91b081b
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@qt.io>

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