Squashed 'src/dmclock/' changes from a9e777f08f..93f760c57c

Squashed 'src/dmclock/' changes from a9e777f08f..93f760c57c

93f760c57c Merge pull request #40 from ivancich/wip-change-client-rec-init
824d92dd3d Merge pull request #38 from ivancich/wip-improve-next-request-return
941d1bef54 Change initialization of IndIntruHeapData to C++'s value-initialization to better future-proof the code. Since at the momeent they are scalars they'll be zero-initialized (i.e., to zero). However if they ever become something more complex, their default constructors will be called.
19153d979f Merge pull request #39 from ivancich/wip-delta-rho-plugin
a94c4e086c Allow the calculations of rho and delta to be handled by a "tracker" specified via template parameter (i.e., by static polymorphism). The tracker follows a simple interface constisting of three functions and one static function.
856a26c466 Clarify code surrounding the return value of do_next_request.
b632cfda4f Merge pull request #37 from ivancich/wip-fix-uninit-data
e6df585153 The coverity scan published in ceph-devel on 2017-09-21 revealed some uninitialized data in a constructor. This fixes that.
165a02542d Merge pull request #34 from TaewoongKim/anticipate
72e4df95cf Make anticipation_timeout configurable with config file
2f06d632d5 Add anticipation duration that keeps from resetting tag values to the current time

git-subtree-dir: src/dmclock
git-subtree-split: 93f760c57c75b9eb88382bcba29fcac3ce365e7f