Add avx512 flags to makevars

[shikokuchuo]

Present on recent Intel processors.

[jwijffels]

Thanks. I based myself on https://github.com/ggerganov/whisper.cpp/blob/master/Makefile to construct the Makevars file. Didn't see avx512 in there. Does it make sense to include it upstream at https://github.com/ggerganov/whisper.cpp/blob/master/Makefile?

[shikokuchuo]

I thought I got a decent speedup, but think I was mistaken... I saw it as an option in the output to whisper_benchmark(model). The issue I'm having is that actually every time I run that benchmark (in the same session), the time increases, not sure what the reason could be.

[jwijffels]

I haven't looked myself into details to this benchmark and didn't spend much time to incorporate the newest changes in that since whisper.cpp version 1.5.4. It is still pretty much the benchmark code which was there in whisper.cpp version 1.2.1.
There are some changes in the benchmark script at whisper.cpp which is taken from here: https://github.com/ggerganov/whisper.cpp/blob/master/examples/bench/bench.cpp so not sure what the reason is myself

If you want to compare your machine to others: ggerganov/whisper.cpp#89