[Bug] Runtime Cross Compile Broken After The FFI Refactor

In Arm China, we are migrating the old work to the newest code, recently the FFI refactor introduce lots of changes in very low level infrastructure, now only the `cython` way is supported, there isn't `ctypes`, when cross compile the AArch64 TVM runtime for RPC server on X86 machine, I found:
1. set USE_LIBBACKTRACE to OFF in config.cmake don't work
2. the `core.cpython-xxx.so` isn't built automatically
3. excute the "python3 setup.py built_ext" command manually will create a X86 `core.cpython-xxx.so`

Is there any way now can do the cross compile for the `core.cpython-xxx.so`?

Start with config.cmake and setup.py, focusing on the cross-compilation path for the AArch64 TVM runtime and the setup.py build_ext entry point. Reproduce the build on an X86 machine, including USE_LIBBACKTRACE=OFF, and determine why core.cpython-xxx.so is not automatically produced for the target. Done means the target-compatible core extension is built without manually creating an X86 extension.

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