C: likely / unlikely userspace macros

likely.c

#if __GNUC__ >= 3
# define likely(x) __builtin_expect(!!(x), 1)
# define unlikely(x) __builtin_expect(!!(x), 0)
#else
# define likely(x) (x)
# define unlikely(x) (x)
#endif

likely2.c

#ifndef UNLIKELY_H
#define UNLIKELY_H
#if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
#define likely(expr) __builtin_expect((expr), 1)
#define unlikely(expr) __builtin_expect((expr), 0)
#else
#define likely(expr) (expr)
#define unlikely(expr) (expr)
#endif
#endif