commit https://github.com/vim/vim/commit/136f29a91dbafce424e31a4af133155f997e8f78 Author: Bram Moolenaar <Bram@vim.org> Date: Sat Feb 27 20:14:15 2016 +0100 patch 7.4.1437 Problem: Old system doesn't have isinf() and NAN. (Ben Fritz) Solution: Adjust #ifdefs. Detect isnan() and isinf() functions with configure. Use a replacement when missing. (Kazunobu Kuriyama)