root@selectron:/root/buildbox# ninja -C build
ninja: Entering directory `build'
[1/25] Generating ''.
FAILED: buildbox@exe/google/api/annotations.pb.cc buildbox@exe/google/api/annotations.pb.h
/usr/local/bin/protoc --proto_path=.. --cpp_out=buildbox@exe ../google/api/annotations.proto
google/protobuf/descriptor.proto: File not found.
google/api/annotations.proto: Import "google/protobuf/descriptor.proto" was not found or had errors.
google/api/annotations.proto:28:8: "google.protobuf.MethodOptions" is not defined.
google/api/annotations.proto: warning: Import google/api/http.proto but not used.