Add slow commands as phosphor instant traces
Add slow commands as phosphor instant traces

We should expand on this to show to entire execution time of the
command. For now, however, this will do.

Change-Id: Iac56095c01a00a07111eeca3b1a7a62a68e73922
Reviewed-on: http://review.couchbase.org/82915
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

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