DLSS Updater 4.2.2

Linux:

1. Fixes for the high performance updater using the Windows path mapping for DLL memory mapping.
2. Fixed Steam libraries whose default install path is a symlink (e.g. Linux's ~/.steam/steam pointing at ~/.local/share/Steam) were scanned twice - once via fast appmanifest-based auto-detection and once via a redundant "manual path" fallback - because the two paths were compared as literal strings instead of their resolved real paths: #240

General:

1. Hardened checks for if_file_in_use to treat a file that disappears between the existence check and the open as not in use, rather than surfacing as an update error.