Collect a block-wise histogram of trim and write errors

Collect a block-wise histogram of trim and write errors

This patch collects information on how many trims or writes each trim
block sized unit can undergo before its first error. It also records
the way in which an error occurred, if one did.

Output is provided with a histogram which can be output either in
normal or json output. Terse output is omitted, since it seemed like
that would require a version rev bump.

Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: Jens Axboe <axboe@fb.com>