Build broken on RPM distros

The build is broken on RPM distros (awslinux, Fedora, Centos, Redhat,...). Their packages for the crypto C++ library are under a different name. Awslinux also doesn't have protobuff 3 support yet.

Interest in a PR to pin to pin dependencies as git submodules like https://github.com/protocolbuffers/protobuf/blob/c981d39d1e3d033c4f00dd48d16e8bdce55a3861/cmake/tests.cmake#L14 ?