reduce chattyness of makefiles

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@48597 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Makefile b/test/Makefile
index f162978..8c8fe51 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -14,6 +14,6 @@
 	      -print -exec ./TestRunner.sh {} \;
 
 clean::
-	rm -rf Output/
+	@ rm -rf Output/
 
 .PHONY: all clean