+#else
+ /*
+ * Turn on _GNU_SOURCE to get everything GNU libc has to offer,
+ * including asprintf(), if we're using GNU libc.
+ *
+ * Unfortunately, one thing it has to offer is a strerror_r()
+ * that's not POSIX-compliant, but we deal with that in
+ * pcapint_fmt_errmsg_for_errno().
+ *
+ * We don't limit this to, for example, Linux and Cygwin, because
+ * this might, for example, be GNU/HURD or one of Debian's kFreeBSD
+ * OSes ("GNU/FreeBSD").
+ *
+ * Avoid redefining, same as below.
+ */
+ #ifndef _GNU_SOURCE
+ #define _GNU_SOURCE
+ #endif
+