build: Add more cross-compilation configurations

[robinlinden]

I tested that the Windows binaries produced by this actually run on Windows. For the macOS configurations, I just checked them w/ file bazel-bin/util/crc32_test to make sure that Bazel produced what I expected, but I didn't run any of them.

[Zer0-One]

Is aarch64 supposed to target apple's M1/M2 chips? Or do those need a separate target entirely? All I know about M1 is that it's "ARM-based".

[robinlinden]

Is aarch64 supposed to target apple's M1/M2 chips? Or do those need a separate target entirely? All I know about M1 is that it's "ARM-based".

Yeah, it's supposedly the M1/M2 chips: https://github.com/uber/hermetic_cc_toolchain/tree/main#host-environments

darwin_amd64, the 64-bit post-PowerPC models.
darwin_arm64, the M1.