[REG 5.12.3 -> 5.12.4] Crash after setting QAccelerometer mode to gravity on Android

Since Qt 5.12.4, a crash occurs when applications try to call QAccelerometer::setAccelerationMode(QAccelerometer::Gravity) on a device which has no Gravity sensor.

The triggers are the same as the crash reported in QTBUG-39335, but:
Despite being a patch release in a LTS branch, Qt 5.12.4 came with a complete rewrite of the Android sensors plugin. The new code in AndroidAccelerometer::applyAccelerationMode(...) does warn about the missing sensor, but continues to apply the mode anyway. According to the documentation, it should not change the mode.