Standalone: Fix some ignored directories in the standard lib path.
Standalone: Fix some ignored directories in the standard lib path.

Before, these directories themselves wouldn't be returned from
scanStandardLibraryPath, but they would still be recursively explored. Now, the
list contents are replaced in-place, so the contents of these directories are
excluded from the walk.

kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka