This function is missing on some platforms:
NetBSD 3.0, HP-UX 11.23, IRIX 6.5, Solaris 9, mingw.
@item
-glibc has an incompatible version of this function. The POSIX compliant code
+glibc and Cygwin have an incompatible version of this function. The
+POSIX compliant code
@smallexample
char *s = (strerror_r (err, buf, buflen) == 0 ? buf : NULL);
@end smallexample