Refactor the library build script to no longer link again

[ghaith]

With whole-archive now working as expected, our workaround to link the stdlib is no longer required.

With this in place, we should be able to simplify the package script for the lib, we now only need to copy the so file, no need for re-linking from the archive in the build.rs

This should be done in a different commit, i'm just referencing it here for us to track

Originally posted by @ghaith in #1566