Added libprotobuf to extract and dump ABI.

Dump textual presentation of the ABI as well for
ease of review.

Test: header-abi-dumper -o example1.dump tests/example1.h -- clang -x
c++ -I . -std=c++11.

Change-Id: I65d90d1ec834d7c30cde4eb389862fd38a4e19e9
6 files changed