Register the *address* of global symbol *name*.  This will make
    it usable (e.g. callable) from LLVM-compiled functions.

def add_symbol(name, address):
    """
    Register the *address* of global symbol *name*.  This will make
    it usable (e.g. callable) from LLVM-compiled functions.
    """
    ffi.lib.LLVMPY_AddSymbol(_encode_string(name), c_void_p(address))