protobuf patch: support MSVC14, aka VStudio 2015
protobuf patch: support MSVC14, aka VStudio 2015

* https://github.com/google/protobuf/issues/240
* https://github.com/google/protobuf/pull/813
* Add GOOGLE_ATTRIBUTE_NOINLINE to GetArena() and GetMaybeArenaPointer() methods.
* This is to avoid "unresolved link" errors in MSVC 2015 during Release build

smanders/externpro