Enable Debug Info in CMakeLists.txt

[haowang0402]

For people who are not super familiar with pybind or cmake, if you want to generate the debug information for the shared library, you will need to comment the line pybind11_strip(ndarray_backend_cpu) and then compile it with regular cmake debug flag. Otherwise, the debug info will get stripped and you could not use debugging tools like (gdb, valgrind, etc.).

[Sstoica24]

Where did you find the "pybind11_strip(ndarray_backend_cpu" line?