dirbuffer-fid-is-index-20050119

dirbuffer-fid-is-index-20050119

"The new buffer code (which I wrote) did not deal
with dcache object re-use, as I had conflated the concepts of "dcache *
reuse" and "dcache slot reuse".

This patch should fix this problem. It now stores the dcache index (aka slot number,
which is the same as the numeric part of the cache file's filename) in the
buffer instead of the ephemeral struct dcache pointer."