Add a tiny protobuf implementation

Add a tiny protobuf runtime in proto.cc and proto.h, and a python
script that takes a binary proto descriptor (produced by
protoc --descriptor_set_out) and produces a .pb.h file that
implements a subset of the protobuf C++ Message interface.

(cherry-picked from commit 55f21672056ecde65ad1b037e8aaaf8d83c3fb95)

Change-Id: I30d89211fb42969836e7fddf912903f6a92b45a5
5 files changed