update Makefile clean targets

Makefile

@@ -88,7 +88,9 @@ bench-%.so: bench-%.c timeout.h
 	$(LUA) bench-expire.lua $< > $@.tmp
 	mv $@.tmp $@
 
-bench.eps: bench.plt $(foreach OP, add del expire, wheel-$(OP).dat heap-$(OP).dat)
+DATS =  $(foreach OP, add del expire, wheel-$(OP).dat heap-$(OP).dat)
+
+bench.eps: bench.plt $(DATS)
 	gnuplot bench.plt > $@.tmp
 	mv $@.tmp $@
 
@@ -98,7 +100,11 @@ bench.pdf: bench.eps
 .PHONY: clean clean~
 
 clean:
-	$(RM) -r timeout timeout8 timeout16 timeout32 timeout64 *.dSYM *.so *.dat *.eps
+	$(RM) timeout timeout8 timeout16 timeout32 timeout64
+	$(RM) test-timeout *.o
+	$(RM) bench.so bench-*.so
+	$(RM) -r *.dSYM
+	$(RM) $(DATS) bench.eps bench.pdf
 
 clean~: clean
 	$(RM) *~