Revert changes that make this incompatible with code generated by thrift 0.8.0

Thrift 0.8.0 is the version of the code generator installed on the Jenkins agents. Since we're not actually particularly bothered about the changes between 0.8.0 and 0.9.* (except for the async support), let's take the pragmatic route and revert these two changes, allowing us to (hopefully) build code generated on jenkins against this libthrift.