Disable some flags in Apple x86_64

[Freed-Wu]

@abetlen reports some flags cannot work in Apple x86_64.
Disable them by default.

https://github.com/abetlen/llama-cpp-python/blob/b4939c2d99cb3b0e49bcaeee8731050deed9ccfe/CMakeLists.txt#L9-L16

[Freed-Wu]

@abetlen, I advise to move https://github.com/abetlen/llama-cpp-python/blob/b4939c2d99cb3b0e49bcaeee8731050deed9ccfe/CMakeLists.txt#L9-L16
to the upstream.

[cebtenzzre]

These are just defaults - they are meant to be changed via the command line if you are on an older processor. This is not an Apple-specific concern.

The build script currently does not warn if you are trying to use flags that are not compatible with the processor you are compiling on. -DLLAMA_NATIVE=ON is what you should be using, which after #3273 is merged will build specifically for the processor you are compiling on, without enabling anything unsupported.

[Freed-Wu]

Thanks, #3273 is awesome.