Rollup merge of #146343 - madsmtm:fix-platform_version, r=tgross35

Weakly export `platform_version` symbols

The symbols `__isPlatformVersionAtLeast` and `__isOSVersionAtLeast`. This should allow linking both `compiler-rt` and `std`, which fixes https://github.com/rust-lang/rust/pull/138944#issuecomment-3266574582.

r? tgross35
CC ``@zmodem,`` could you please verify that this works for you?