During the LLVM 18 upgrade, two changes were made that changed `@alignOf(u64)` to 4 for the x86-windows target:

- `Type.maxIntAlignment` was made to return 16 for x86 (200e06b). Before that commit, `maxIntAlignment` was 8 for windows/uefi and 4 for everything else
- `Type.intAbiAlignment` was made to return 4 for 33...64 (7e1cba7 + e89d6fc). Before those commits, `intAbiAlignment` would return 8, since the maxIntAlignment for x86-windows was 8 (and for other targets, the `maxIntAlignment` of 4 would clamp the `intAbiAlignment` to 4)

`src/codegen/llvm.zig` has its own alignment calculations that no longer match the values returned from the `Type` functions. For the x86-windows target, this loop:

https://github.com/ziglang/zig/blob/ddcb7b1c11f88c4ae150b36807033060a469dcb5/src/codegen/llvm.zig#L558-L567

when the `size` is 64 will set `abi` and `pref` to 64 (meaning an align of 8 bytes), which doesn't match the `Type` alignment of 4.

This commit makes `Type.intAbiAlignment` match the alignment calculated in `codegen/llvm.zig`.

Fixes #20047
Fixes #20466
Fixes #20469