Fix tarball issues

[dag-erling]

• Always pass -f to tar rather than rely on non-standard behavior.
• Sort and deduplicate file list to prevent multiple inclusion of the same file in the tarball.

[pts]

Thank you! I've updated https://github.com/pts/sam2p/releases/download/v0.49.4/sam2p-0.49.4.tar.gz by rerunning mkdist.sh.