Difficulties of building this project in my environment

[huanggh666]

My computer system is ubuntu 18 and has no network connection. I have installed the protobuf and libprotobuf-mutator in the custom directory. Therefore cmake can not find it using find_package() method. How to build it in this situation? I try to modify the CMakelist.txt and build it. Then, an error that 'const Root' is not a pointer... in the test_fuzzer.cc:37 switch(input->test()) is report when run make. I disable adding example in the CMakelist.txt and make it again. However the head file afl_mutator.h is not in ./build/src after running make correctly.