Remove std.dll from dist archives on Windows

[Kobzol]

Thanks to #122362, librustc_driver.so no longer dynamically links to the standard library (libstd.so). And since #131188, we no longer ship the dynamic libstd file on non-Windows platforms. This reduces the size of the dist rustup components that we ship.

However, we still ship std.dll on Windows, because removing it was causing incremental tests to fail in the post-optimization testing done by the opt-dist tool. More information can be found here.