patch 8.1.0605: running make in the top directory echoes a comment

Problem:    Running make in the top directory echoes a comment.
Solution:   Prefix with @. (closes #3698)
diff --git a/Makefile b/Makefile
index 2155b58..6cbdc72 100644
--- a/Makefile
+++ b/Makefile
@@ -39,7 +39,7 @@
 	@echo "Starting make in the src directory."
 	@echo "If there are problems, cd to the src directory and run make there"
 	cd src && $(MAKE) $@
-	# When the target is "test" also run the indent tests.
+	@# When the target is "test" also run the indent tests.
 	@if test "$@" = "test"; then \
 		$(MAKE) indenttest; \
 	fi