* Added PGV C++ generation support. This (hopefully temporarily)
abandons using native proto_library in favor of pgv_cc_proto_library.
We maintain build support for proto_library for the glorious future in
which we write a Bazel aspect to run PGV against the native
proto_library shadow graph.
* Replace min_len with min_bytes on strings, until PGV gets not-empty or
min_len support for C++.
* Various fixups for places where the PGV plugin objected to
annotations.
Signed-off-by: Harvey Tuch <htuch@google.com>
alyssawilk
htuch