Avoid repeated rebuilds of 'wipe'

package/wipe/wipe.mk

@@ -29,9 +29,10 @@ $(WIPE_DIR)/.unpacked: $(DL_DIR)/$(WIPE_SOURCE) $(DL_DIR)/$(WIPE_PATCH)
 	touch $(WIPE_DIR)/.unpacked
 
 $(WIPE_DIR)/.configured: $(WIPE_DIR)/.unpacked
-	touch  $(WIPE_DIR)/.configured
+	touch  $@
 
 $(WIPE_DIR)/$(WIPE_BINARY): $(WIPE_DIR)/.configured
+	rm -f $(WIPE_DIR)/$(WIPE_BINARY)
 	$(MAKE) CC=$(TARGET_CC) -C $(WIPE_DIR)  generic
 
 $(TARGET_DIR)/$(WIPE_TARGET_BINARY): $(WIPE_DIR)/$(WIPE_BINARY)