FindBugs' FE.FE_FLOATING_POINT_EQUALITY is about double value inaccuracies, not
about NaN or negative zero (which is the topic of java.lang.Double.equals vs.
==).

Reuse existing qa.TestCaseOldAPI.approxEqual method, moved to util.utils.

Change-Id: I65f7bb1faf921e1c4035bb96aeff1eaf2cfb3153