Added -f option to rm in clean command.

Makefile

@@ -3,7 +3,7 @@ output: dwmblocks.o
 dwmblocks.o: dwmblocks.c blocks.h
 	gcc -c -lX11 dwmblocks.c 
 clean:
-	rm *.o *.gch dwmblocks
+	rm -f *.o *.gch dwmblocks
 install: output
 	mkdir -p /usr/local/bin
 	cp -f dwmblocks /usr/local/bin