Also make the script fetch protoc from the usual place.

On account of https://github.com/google/protobuf/pull/1712

The SwiftSample doesn’t build in this commit, but I need to sync with
head anyway so I’ll first merge v1.0.x into this branch and then debug.

Not after :) This fixes the local server tests failing to SSL handshake.

Still missing: Catch the C-library error to improve the error message.

C++ Compression Level set properly