[net] Signal NODE_COMPACT_FILTERS if we're serving compact filters.

If -peerblockfilters is configured, signal the NODE_COMPACT_FILTERS service
bit to indicate that we are able to serve compact block filters, headers
and checkpoints.

src/protocol.cpp

@@ -213,6 +213,7 @@ static std::string serviceFlagToStr(size_t bit)
     case NODE_GETUTXO:         return "GETUTXO";
     case NODE_BLOOM:           return "BLOOM";
     case NODE_WITNESS:         return "WITNESS";
+    case NODE_COMPACT_FILTERS: return "COMPACT_FILTERS";
     case NODE_NETWORK_LIMITED: return "NETWORK_LIMITED";
     // Not using default, so we get warned when a case is missing
     }