+/* We don't bother checking for IPv6 support; the checks done in the
+ autoconf script are relics of a bygone age, where IPv6 support in
+ OSes was sometimes present by default, sometimes provided by
+ third-party add-ons, and sometimes completely absent, and where the
+ particular flavor of IPv6 support mattered to us. We'll just wire it
+ on, unless and until that becomes an issue on platforms where people
+ use CMake. */
+#define INET6 1