#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
ssize_t preadv (int, const struct iovec *, int, off_t);
ssize_t pwritev (int, const struct iovec *, int, off_t);
-#if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
+#if defined(_LARGEFILE64_SOURCE)
#define preadv64 preadv
#define pwritev64 pwritev
#define off64_t off_t