Add support for NetBSD

While I only checked on NetBSD 7.0, it seems to use the same
rc system as FreeBSD so it should be working for now.

lib/ansible/modules/system/hostname.py

@@ -727,6 +727,11 @@ class FreeBSDHostname(Hostname):
     distribution = None
     strategy_class = FreeBSDStrategy
 
+class NetBSDHostname(Hostname):
+    platform = 'NetBSD'
+    distribution = None
+    strategy_class = FreeBSDStrategy
+
 
 # ===========================================