The manifest asks for android:screenOrientation="fullUser", but SDL
overrides it at window creation: SDLActivity.setOrientationBis, given a
resizable window and no SDL_HINT_ORIENTATIONS -- which is what conf.lua
produces on Android -- requests SCREEN_ORIENTATION_FULL_SENSOR. The
*_SENSOR constants follow the accelerometer even when the player has
turned auto-rotate off, so the game rotated anyway on a locked device.
Override setOrientationBis in GameActivity to remap SDL's request onto
the matching *_USER constant after super has run. The same orientations
stay allowed and SDL keeps deciding which ones those are; only the
tie-break changes, from the sensor to the system rotation setting.