Fix output of NaN on msvc-14.

Previous versions outputted `1.#IND`, now the output is `nan(ind)` for an indefinite NaN (conformance to C99).

See: http://blogs.msdn.com/b/vcblog/archive/2014/06/18/crt-features-fixes-and-breaking-changes-in-visual-studio-14-ctp1.aspx