Add clean rule to makefile

Author: jsks

Makefile

@@ -1,7 +1,7 @@
 PID := $(shell cat .czhttpd-pid 2>/dev/null)
 
 all: test
-.PHONY: start debug reload test stress
+.PHONY: start debug reload test stress clean
 
 start:
 	@zsh -f test/start.sh
@@ -17,3 +17,6 @@ test:
 
 stress:
 	@zsh -f test/stress/stress.sh -l stress.log $(CLI_ARGS)
+
+clean:
+	rm -rf {test,stress}.log test/stress/{html,report}