遇到错误如下：
/grpc/gens/src/proto/grpc/core/stats.pb.cc:187:13: error: ‘dynamic_init_dummy_src_2fproto_2fgrpc_2fcore_2fstats_2eproto’ defined but not used [-Werror=unused-variable]
static bool dynamic_init_dummy_src_2fproto_2fgrpc_2fcore_2fstats_2eproto = []()
^
cc1plus: all warnings being treated as errors
找到Makefile，去掉其中-Werror ，重新编译。
