_POSIX_C_SOURCE   265 sys/cdefs.h    #ifdef _POSIX_C_SOURCE
_POSIX_C_SOURCE   266 sys/cdefs.h    # if (_POSIX_C_SOURCE - 0 >= 200112)
_POSIX_C_SOURCE   269 sys/cdefs.h    # elif (_POSIX_C_SOURCE - 0 >= 199506)
_POSIX_C_SOURCE   272 sys/cdefs.h    # elif (_POSIX_C_SOURCE - 0 >= 199309)
_POSIX_C_SOURCE   275 sys/cdefs.h    # elif (_POSIX_C_SOURCE - 0 >= 2)