Also, use `cmake --build` instead of manually calling `gmake`. This
allows us to maybe later use `ninja` instead of `gmake` without changing
this build invocation.
Also, increase timeout to 120 seconds. FreeBSD tests are slow.
It doesn't work at all, because we're missing something in the net code
to do with endian conversions. I haven't investigated, yet, but at least
now we have a failing test that can be investigated.
Also moved to cmake 3.5 at minimum. CMake will stop supporting lower
versions than that, soon.
Also moved to C11 from C99 to get `static_assert`.
Also made a network ERROR into a WARNING. It triggers on FreeBSD.
