mkdir with -p

Makefile

@@ -64,9 +64,9 @@ tools: haxelib haxedoc
 install:
 	cp haxe $(INSTALL_DIR)/bin/haxe
 	rm -rf $(INSTALL_DIR)/lib/haxe/std
-	-mkdir $(INSTALL_DIR)/lib/haxe
+	-mkdir -p $(INSTALL_DIR)/lib/haxe
 	svn export std/ $(INSTALL_DIR)/lib/haxe/std
-	-mkdir $(INSTALL_DIR)/lib/haxe/lib
+	-mkdir -p $(INSTALL_DIR)/lib/haxe/lib
 	chmod -R a+rx $(INSTALL_DIR)/lib/haxe
 	chmod 777 $(INSTALL_DIR)/lib/haxe/lib
 	cp std/tools/haxelib/haxelib.sh $(INSTALL_DIR)/bin/haxelib