MB-22005 Fix ep-engine_sizes to return correct size of Histogram<>
MB-22005 Fix ep-engine_sizes to return correct size of Histogram<>

Use Histogram<>::getMemFootPrint() method so we can correctly
calculate the memory foot print of a given Histogram<T>. As
before this we incorrectly calculated its size in ep-engine_sizes.

Also add class HdrMicroSecHistogram to ep-engine_sizes.

Change-Id: I2c58fd009a19ccce7fadba9c070a315f1675020c
Reviewed-on: http://review.couchbase.org/105855
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine