Ok, I prepared Python for monotonic clock, I attached an updated patch. It is now much simpler.

pymonotonic-3.patch:

* time.monotonic() is now always available

* _PyTime_Init() ensures that the operating system provides a monotonic clock and that the clock works

* Python 3.5 now requires a monotonic clock. All operating systems supported by Python 3.5 provides a monotonic clock. GNU Hurd doesn't, but it is not supported.

* drop try/except ImportError around "from time import monotonic"

* use a monotonic clock in _thread, gc and socket modules to compute elapsed time and timeouts