[net processing] Message handling for getcfheaders.

if -peerblockfilters is configured, handle requests for cfheaders.

src/protocol.cpp

@@ -40,6 +40,8 @@ const char *SENDCMPCT="sendcmpct";
 const char *CMPCTBLOCK="cmpctblock";
 const char *GETBLOCKTXN="getblocktxn";
 const char *BLOCKTXN="blocktxn";
+const char *GETCFHEADERS="getcfheaders";
+const char *CFHEADERS="cfheaders";
 const char *GETCFCHECKPT="getcfcheckpt";
 const char *CFCHECKPT="cfcheckpt";
 } // namespace NetMsgType
@@ -73,6 +75,8 @@ const static std::string allNetMessageTypes[] = {
     NetMsgType::CMPCTBLOCK,
     NetMsgType::GETBLOCKTXN,
     NetMsgType::BLOCKTXN,
+    NetMsgType::GETCFHEADERS,
+    NetMsgType::CFHEADERS,
     NetMsgType::GETCFCHECKPT,
     NetMsgType::CFCHECKPT,
 };