SF: fix floating-point-exception in SurfaceFlinger::setCompositorTimingSnapped

    // something (such as user input) to an accurate diasplay time.

    // Snapping also allows an app to precisely calculate

    // mVsyncConfiguration->getCurrentConfigs().late.sf with (presentLatency % interval).

    nsecs_t bias = stats.vsyncPeriod / 2;

    int64_t extraVsyncs = (compositeToPresentLatency - idealLatency + bias) / stats.vsyncPeriod;

    nsecs_t snappedCompositeToPresentLatency =

    const nsecs_t bias = stats.vsyncPeriod / 2;

    const int64_t extraVsyncs = (stats.vsyncPeriod) > 0 ?

        ((compositeToPresentLatency - idealLatency + bias) / stats.vsyncPeriod) :

        0;

    const nsecs_t snappedCompositeToPresentLatency =

            (extraVsyncs > 0) ? idealLatency + (extraVsyncs * stats.vsyncPeriod) : idealLatency;

    std::lock_guard<std::mutex> lock(getBE().mCompositorTimingLock);