conclusion for cxxtools
According to a few days' research, I find out the reason why getting errors when building the cxxtools on aarch64, but even I change the source code I can't make it built successful.. Maybe I need to change the compile command parameters to force it ignoring the warnings.
Conclusion for cxxtools:
Not much. The cxxtools' source codes include the code for arm architecture, and we don't need to modify the source code.
Even I find the problem (see my last post), I can't solve it by modifying source code, maybe I need to modify the building commands' parameters. For now I cant build it successfully.