Drop autotools build (or leave it as a thin wrapper around CMake).

Now that CMake build is usable for production (at least, in some configurations and with very specific package managers), the next step is to get rig of the need to maintain two separately configured build systems.

To get rid of the automake build (or turn it into a deprecated thin wrapper around the CMake build), we need to reach a feature parity between automake and cmake, at least for actively used features.

Deprecating automake will greatly simplify all the things that require dealing with build system: adding/removing/bundling/unbundling dependencies, changing source files layout, fixing build system quirks and so on.

CMake build improvements that are not blocking autotools build deprecation are out of scope of this epic.