Protobuffs generates insufficient type information for its records.

Resolves:

riak_pb_codec.erl:338: Invalid type specification for function riak_pb_codec:decode_commit_hooks/1. The success typing is ([any()]) -> [{atom(),atom() | [any(),...]} | {'modfun',atom(),atom() | [any(),...]}]

Calls within riak_pb only pass empty lists in place of
type_mappings(), but riak_kv will pass its own ?MOD_MAP. This results
in a false warning in encode_type/2.

Resolves:

riak_pb_dt_codec.erl:181: The pattern {AtomType, _} can never match the type 'false'

Resolves:

riak_pb_search_codec.erl:45: Invalid type specification for function riak_pb_search_codec:decode_search_doc/1. The success typing is (#rpbsearchdoc{fields::[{_,_,_}]}) -> [{[any()],[any()]}]

Resolves:

Unknown types:
  riakc_obj:metadata/0
  riakc_obj:value/0

This is a library application, so all the exported functions in
generated code are potentially used elsewhere.