chrony/test/simulation

This is a collection of simulation tests using the clknetsim simulator
(supported on Linux only).

https://github.com/mlichvar/clknetsim

The CLKNETSIM_PATH environment variable should point to the directory where
clknetsim was downloaded and compiled. If the variable is not set, the tests
will look for clknetsim in ./clknetsim in the current directory.

The tests are written in bash and they can be run directly. The ./run script
runs all tests.