This decreases total testing time by over a minute on my old Mac Pro.
It probably has much less effect on systems with fewer cores, but shouldn't
be any worse there.
Swift SVN r22745
the type
Printing Float32 with %0.15g not only wastes screen space, but also causes
confusion for users, and pretends that a Float32 has more precision than it
actually does.
rdar://18043123
Swift SVN r21435
