message: Fix MacOS fuzzing link issues
diff: // e.g. the one that comes from a bug report.
  #include <cassert>
  -#include <iostream>
  #include <fstream>
  +#include <iostream>
  #include <vector>
  +// Define LLVMFuzzerMutate to avoid link failures for targets that use it
  +// with libFuzzer's LLVMFuzzerCustomMutator.
  +extern "C" size_t LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize) {
  + assert(false && "LLVMFuzzerMutate should not be called from afl_driver");
  + return 0;
  +}
  +
  // Forward declare the "fuzz target" interface.
  // We deliberately keep this inteface simple and header-free.
  extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
  