closes#22369, closes#23197, closes#24385, refs #21328
According to #21328 the standard library on Unix should be installed in
`/usr/lib/nim/lib`, however the installer was not updated for this
change, hence the problem as described in
https://github.com/nim-lang/Nim/issues/23197#issuecomment-2031386896.
Have not tested if this fixes the problem but the comment heavily
implies it does. The problem is also in 2.0 so it could be backported
but I can't say for sure that it works and doesn't break anything.