ref: a70379d7e4b822f532fb0a8ccdd1624a90b64a68
dir: /src/nan.h/
#pragma once
#if defined(__plan9__)
extern double D_PNAN, D_PINF;
#else
#define D_PNAN __builtin_nan("")
#define D_PINF __builtin_inf()
#endif
extern double D_NNAN, D_NINF;
void nan_init(void);