`freeze-stdlib` is broken on windows

Since the symlink is non-functional on windows.

The following works as a patch for me:
```rust
#[cfg(feature = "freeze-stdlib")]
pub const FROZEN_STDLIB: &rustpython_compiler_core::frozen::FrozenLib =
    rustpython_derive::py_freeze!(dir = "../Lib", crate_name = "rustpython_compiler_core");
```
I don't know if there are unintended consequences however.
