mirage-ptime -- a POSIX clock for MirageOS

This library implements portable support for an operating system timesource that is compatible with the MirageOS library interfaces found in: https://github.com/mirage/mirage

It implements Mirage_ptime which is a clock that counts time since the Unix epoch.

The following sources are used:

• The Unix version uses Ptime_clock,
• The freestanding version uses the paravirtual clock source from the hypervisor.