build: fix STAGING_DIR cleaning for packages

This fixes two issues with cleaning package files from STAGING_DIR:

* CleanStaging currently can only remove files and not directories. This
  changes CleanStaging to use clean-package.sh, which does remove
  directories.

* Because of the way directories are ordered in the staging files list,
  clean-package.sh currently tries (and fails) to remove parent
  directories before removing subdirectories. This changes
  clean-package.sh to process the staging files list in reverse, so that
  subdirectories are removed first.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

include/package.mk

@@ -81,9 +81,10 @@ STAGING_FILES_LIST:=$(PKG_DIR_NAME)$(if $(BUILD_VARIANT),.$(BUILD_VARIANT),).lis
 define CleanStaging
 	rm -f $(STAMP_INSTALLED)
 	@-(\
-		cd "$(STAGING_DIR)"; \
-		if [ -f packages/$(STAGING_FILES_LIST) ]; then \
-			cat packages/$(STAGING_FILES_LIST) | xargs -r rm -f 2>/dev/null; \
+		if [ -f $(STAGING_DIR)/packages/$(STAGING_FILES_LIST) ]; then \
+			$(SCRIPT_DIR)/clean-package.sh \
+				"$(STAGING_DIR)/packages/$(STAGING_FILES_LIST)" \
+				"$(STAGING_DIR)"; \
 		fi; \
 	)
 endef

scripts/clean-package.sh

@@ -14,7 +14,7 @@ cat "$1" | (
 		[ -f "$entry" ] && rm -f $entry
 	done
 )
-cat "$1" | (
+sort -r "$1" | (
 	cd "$2"
 	while read entry; do
 		[ -n "$entry" ] || break