Change assertions in Stats.c to warnings (and introduce WARN macro)wip/t20899

ASSERT should be used in situations where something very bad will happen
later on if a certain invariant doesn't hold. The idea is that IF we
catch the assertion earlier then it will be easier to work out what's
going on at that point rather than at some indeterminate point in the
future of the program.

The assertions in Stats.c do not obey this philsophy and it is quite
annoying if you are running a debug build (or a ticky compiler) and one
of these assertions fails right at the end of your program, before the
ticky report is printed out so you don't get any profiling information.

Given that nothing terrible happens if these assertions are not true, or
at least the terrible thing will happen in very close proximity to the
assertion failure, these assertions use the new WARN macro which prints
the assertion failure to stdout but does not exit the program.

Of course, it would be better to fix these metrics to not trigger the
assertion in the first place but if they did fail again in the future it
is frustrating to be bamboozled in this manner.

Fixes #20899

0 files changed, 0 insertions, 0 deletions