Regression from [0] based on the incorrect assumption that X11's
Time was a uint64. Despite the `Time` type being 8 bytes,
the value wraps at UINT32_MAX.
Details:
- GHOST_SystemX11::m_start_time now uses CLOCK_MONOTONIC instead of
gettimeofday(..) since event times should always increase.
- Event timestamps now accumulate uint32 rollover.
[0]: efef709ec7