// FreeBSD takes a different approach to _ISOC99_SOURCE: on FreeBSD it
// means "I want *just* C99 things", whereas on GNU libc and Solaris
// it means "I also want C99 things".
//
// On both GNU libc and FreeBSD, _ISOC99_SOURCE is implied by
// _XOPEN_SOURCE==600, but on Solaris it is an error to omit it.
// FreeBSD takes a different approach to _ISOC99_SOURCE: on FreeBSD it
// means "I want *just* C99 things", whereas on GNU libc and Solaris
// it means "I also want C99 things".
//
// On both GNU libc and FreeBSD, _ISOC99_SOURCE is implied by
// _XOPEN_SOURCE==600, but on Solaris it is an error to omit it.