[bazel] add support for platforms and toolchains (Bazel 8 compatibility)

[DoDoENT]

I'm using Bazel 8 with bzlmod and pulled cpuinfo via Bazel Central Registy.

However, when I build my target that depends on cpuinfo for Android platforms, I get compile error in src/arm/mach/init.c which for some reason gets selected because my host machine is MacOS. I've tried the same on Linux but to no avail.

In general, all config_settings should be updated to use standard platforms