net: narrow include scope after moving to netaddress

Net functionality is no longer needed for CAddress/CAddrman/etc. now that
CNetAddr/CService/CSubNet are dumb storage classes.

src/test/addrman_tests.cpp

@@ -7,6 +7,7 @@
 #include <boost/test/unit_test.hpp>
 
 #include "hash.h"
+#include "netbase.h"
 #include "random.h"
 
 using namespace std;