Add times to counters in SHOW STATUS

(proposed by Baron)

Simply adding timers and sizes to the existing counters.
The storage engine API would be the most helpful thing; timing for file
accesses would be the next thing. So for example, if you do

SHOW STATUS LIKE 'Handler%';

You should see Handler_write, Handler_write_time, Handler_write_bytes
(optional).

This would already be better than the Performance Schema in my opinion!
I think we should avoid gettimeofday and use clock_gettime instead for
high-resolution low-overhead timing. I think this is more important
and easier than the ring buffer of SQL statements.

After adding this for the Handler calls, I would suggest adding it for
most or all of the other counters.