Is it currently possible to pass -mtune option to gcc?

[mlowicki]

I would like to experiment with builds optimised for a specific ARM processor via -mtune or -mcpu. Went through https://github.com/gyscos/zstd-rs/blob/main/zstd-safe/zstd-sys/build.rs but I don't any option to set it. We use zstd-rs as one of our deps so doing sth via e.g. env var would be great.