MINOR: connection: report the mux names in "haproxy -vv"

Since the mux names appear at a few places (dumps etc), let's list
them in front of supported mux protocols in "haproxy -vv".
diff --git a/include/proto/connection.h b/include/proto/connection.h
index 8a2884e..ede3726 100644
--- a/include/proto/connection.h
+++ b/include/proto/connection.h
@@ -1002,8 +1002,8 @@
 		else
 			side = "NONE";
 
-		fprintf(out, " %15s : mode=%-10s side=%s\n",
-			(proto.len ? proto.ptr : "<default>"), mode, side);
+		fprintf(out, " %15s : mode=%-10s side=%-8s  mux=%s\n",
+			(proto.len ? proto.ptr : "<default>"), mode, side, item->mux->name);
 	}
 }