_main()?

/* When you make a function called main() in a GCC program, it wants
   this stuff too. */
void _main() { }

That comment is a lie, isn't it?

They are confused about what happens once it is compiled.  Your function named "main" gets converted internally to a symbol called "_main".  Compile "int main() { return 0; }" using gcc and then run nm on it to verify.