freebsd11_network -> freebsd_network.

FreeBSD 12 has no major changes to the ifnet KPIs that constitute a
source compatibility break, save a single one related to locking
which doesn't really apply to us, and so we don't need to create
a "freebsd12_network" directory to work through the upgrades.

src/bin/network/ifconfig/ifconfig.cpp

@@ -27,8 +27,8 @@
 #include <NetServer.h>
 
 extern "C" {
-#	include <freebsd11_network/compat/sys/cdefs.h>
-#	include <freebsd11_network/compat/sys/ioccom.h>
+#	include <freebsd_network/compat/sys/cdefs.h>
+#	include <freebsd_network/compat/sys/ioccom.h>
 #	include <net80211/ieee80211_ioctl.h>
 }