'Fix unresolved symbols if they are defined.'

def resolve(self, engine):

    pending = [name for name in self._unresolved if (name in self._defined)]
    for name in pending:
        fnptr = engine.get_function_address(name)
        ptr = self._unresolved[name]
        ptr.value = fnptr
        self._resolved.append((name, ptr))
        del self._unresolved[name]
