Comment 0 for bug 1619616

mir fails to build with protobuf3. build logs at
https://launchpad.net/ubuntu/+source/mir/0.24.0+16.10.20160815.3-0ubuntu2

In file included from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/server/frontend/protobuf_message_processor.cpp:24:0:
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h: In function ‘void mir::frontend::detail::invoke(Self*, Server*, void (ServerX::*)(const ParameterMessage*, ResultMessage*, google::protobuf::Closure*), const mir::frontend::detail::Invocation&)’:
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h:68:13: error: ‘NewPermanentCallback’ is not a member of ‘google::protobuf’
             google::protobuf::NewPermanentCallback<
             ^~~~~~
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h:68:13: note: suggested alternative:
In file included from /usr/include/google/protobuf/stubs/common.h:48:0,
                 from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/obj-x86_64-linux-gnu/src/protobuf/mir_protobuf.pb.h:9,
                 from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/common/mir/protobuf/display_server.h:22,
                 from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/server/frontend/display_server.h:22,
                 from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/server/frontend/protobuf_message_processor.cpp:19:
/usr/include/google/protobuf/stubs/callback.h:524:36: note: ‘google::protobuf::internal::NewPermanentCallback’
 inline ResultCallback2<R, A1, A2>* NewPermanentCallback(
                                    ^~~~~~~~~~~~~~~~~~~~
In file included from /«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/server/frontend/protobuf_message_processor.cpp:24:0:
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h:69:21: error: expected primary-expression before ‘,’ token
                 Self,
                     ^
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h:70:43: error: expected primary-expression before ‘,’ token
                 ::google::protobuf::uint32,
                                           ^
/«BUILDDIR»/mir-0.24.0+16.10.20160815.3/src/include/server/mir/frontend/template_protobuf_message_processor.h:71:59: error: expected ‘(’ before ‘>’ token
                 typename result_ptr_t<ResultMessage>::type>(
                                                           ^