[3.0] contrib/tools: update protoc/protobuf to 3.4.1

This version with the CVE-2015-5237 fix, without std::mutex and without CompareString internal function that is a define on Windows.

Now the generated code depends on the protobuf version to avoid mistmatches.

This is the version now found in the Windows Docker images.

Draft as it contains a backport of !7740 (merged)