Correct a false comment

targets.h

@@ -172,8 +172,7 @@ public:
   Target *next_target();
 };
 
-/* Ports is the list of ports the user asked to be scanned (0 terminated),
-   you can just pass NULL (it is only a stupid optimization that needs it) */
+/* ports is used to pass information about what ports to use for host discovery */
 Target *nexthost(HostGroupState *hs,const addrset *exclude_group,
                  struct scan_lists *ports, int pingtype);
 int load_exclude_file(addrset *exclude_group, FILE *fp);