luxfi/node required this module and also carried its own cache package, and
the one file the two did not share was lru_sized_cache.go. It is here now,
with the cachetest helper its test uses.
It reached for utils.Zero, and luxfi/utils reaches constants, which reached
geth, which reaches crypto — a chain no cache should pull in to name the zero
value of a type parameter. The helper is four lines here instead.
lru's TestCacheWithEvictionCallback fails before and after this commit; that
directory is untouched.
Co-authored-by: Hanzo Dev <[email protected]>
