* Mark several C macros imported from <float.h> as deprecated.
These macros all have straightforward replacements in terms of static properties on FloatingPoint or BinaryFloatingPoint. It is necessary to add 1 in a few places because of differences between how C and Swift count significand bits and normalize the significand, but this is expected to have minimal impact on code in practice (and when it does have impact, using the Swift definition is generally simpler).
* Address review notes from @moiseev.
This fixes <rdar://problem/27871465>
