Some efforts to get rid of "long" in our codebase

I was playing around with the following imperfect regex to try and get
an idea of how many "long" usages we have.

git grep -E "^\s*(static)?\s*(unsigned)?\s*long\b" -- '*.c' '*.h' | wc -l

REL_13_STABLE -> 486
REL_14_STABLE -> 482
REL_15_STABLE -> 476
REL_16_STABLE -> 485
REL_17_STABLE -> 449
REL_18_STABLE -> 439
master -> 386

(Generally trending downwards with quite a good reduction since v18)

Many of the "long" usages are genuine, e.g for compatibility with
library functions, or in snprintf.c for the %ld and %lu format
specifiers; those we need. However, many of these we don't need. Many
are a possible source of bugs due to not all platforms we support
having the same idea about how wide longs are. We've had and fixed
bugs around this before.

I've attached a couple of patches to get the ball rolling.

0001: CATCACHE_STATS is using signed longs as counters for cache
hits/misses etc. I've changed this to uint64 rather than int64 as I
didn't see the need to have a signed type to count the occurrences of
an event. Maybe there's an anti-universe where negative occurrences
are a thing, but they're not in this one. If something goes awry with
the counters and that causes the subtraction that's being done to
wrap, then we're more likely to notice the bug via the excessively
large number the wrap would end up displaying.

0002: MemSet / MemSetAligned macros. It's probably about time someone
made these disappear, but that's likely for another thread with more
research than I'd like to do here. I replaced "long" with "Size". I
also considered "uintptr_t", but after some reading of the C standard,
I settled on Size as it seems it's possible for platforms to exist
where the pointer width is smaller than the processor's width. I
suspect it might not matter for the platforms we support? Size could
also be smaller than the processor's width, but I feel that's less
likely.

Which yields a drop in the Ocean fewer longs...

0001+0002 -> 367

David