$ man pkg-config
--static Output libraries suitable for static linking. That means including any private libraries in the output. This relies on proper tag‐ ging in the .pc files, else a too large number of libraries will ordinarily be output.
以examples/cpp/route_guide 为例：
修改make file:
1、给 pkg-config 添加 --static 选项：
LDFLAGS += -L/usr/local/lib `pkg-config --libs --static protobuf grpc++`\ -pthread\ -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed\ -ldl
2、CPPFLAGS， CXXFLAGS ，LDFLAGS 分别加上 -static
