Use mimalloc as the default allocator for some targets

[chirizxc]

main repo: https://github.com/microsoft/mimalloc

rust crate: https://github.com/purpleprotocol/mimalloc_rust

For some targets, this provides approximately a 10-15% speed increase.

[chirizxc]

It was interesting to see the benchmarks on your hardware, and I also noticed that your processor is not included in the current benchmarks.

[awolverp]

I also noticed that your processor is not included in the current benchmarks.

Hello. Oh yes I get it now. That text was generated by Python, which is why I did not recognize it.

For some targets, this provides approximately a 10-15% speed increase.

Thank you so much. I will merge this PR ASAP.