Remove bin directory and its contents on make clean
diff --git a/testcases/Makefile b/testcases/Makefile
index a5e76e8..481bb90 100644
--- a/testcases/Makefile
+++ b/testcases/Makefile
@@ -8,6 +8,6 @@
 	@set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i install ; done
 
 clean:
-	rm -rf bin/*
+	rm -rf bin/
 	@set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i clean ; done