Yet another iteration of the tied algorithm: some packages contain

Yet another iteration of the tied algorithm: some packages contain
several hundred copies of the same file (even thousands! I'm looking at you
sdcc), so matching through a list is O(n^2).

So hash the hashes on the actual file name so that we match directly if
the same name file didn't change, and use the first entry otherwise, since
the name won't match.

speeds up updating of texlive somewhat, and makes a huge difference for sdcc.