Remove automatic download and compilation of clknetsim. If clknetsim is
not found, skip all simulation tests, but don't fail "make check".
Also, respect the CLKNETSIM_PATH environment variable.
Use clknetsim to run multiple chronyd instances with simulated clocks
and network. It allows fast and reproducible testing, without real
network.
Included are several tests of performance in different clock/network
conditions, chronyd options, NTP authentication, chronyc, and past bug
fixes.
