check-whitespace: make it quieter.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Makefile

@@ -253,7 +253,7 @@ check-bolt: check-bolt.o $(CCAN_OBJS)
 check-bolt.o: $(CCAN_HEADERS)
 
 check-whitespace:
-	if grep -n '[ 	]$$' Makefile daemon/test/Makefile daemon/Makefile bitcoin/Makefile check-bolt.c $(CORE_SRC) $(BITCOIN_SRC) $(DAEMON_SRC); then echo Extraneous whitespace found >&2; exit 1; fi
+	@if grep -n '[ 	]$$' Makefile daemon/test/Makefile daemon/Makefile bitcoin/Makefile check-bolt.c $(CORE_SRC) $(BITCOIN_SRC) $(DAEMON_SRC); then echo Extraneous whitespace found >&2; exit 1; fi
 
 check-source: check-makefile check-source-bolt check-whitespace	\
 	$(CORE_SRC:%=check-src-include-order/%)		\