Include Apache compliance files in binary packages

Add LICENSE, NOTICE, and DISCLAIMER files to the package target
in Makefile to ensure Apache project compliance requirements are
met when distributing binary releases.

These files are now copied to the package directory alongside the
binaries and install script, and will be included in the final
tar.gz distribution.

Author: tuhaihe

Makefile

@@ -178,6 +178,10 @@ package:
 	@GOOS=$(GOOS) GOARCH=$(GOARCH) CGO_ENABLED=$(CGO) go build -tags '$(RESTORE)' -o $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/bin/$(RESTORE) --ldflags '-X $(RESTORE_VERSION_STR)'
 	@GOOS=$(GOOS) GOARCH=$(GOARCH) CGO_ENABLED=$(CGO) go build -tags '$(HELPER)' -o $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/bin/$(HELPER) --ldflags '-X $(HELPER_VERSION_STR)'
 	@GOOS=$(GOOS) GOARCH=$(GOARCH) CGO_ENABLED=$(CGO) go build -tags '$(S3PLUGIN)' -o $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/bin/$(S3PLUGIN) --ldflags '-X $(S3PLUGIN_VERSION_STR)'
+	@echo "Copying Apache compliance files..."
+	@cp LICENSE $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/
+	@cp NOTICE $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/
+	@cp DISCLAIMER $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/
 	@echo "Creating install script..."
 	@echo '#!/bin/bash' > $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/install.sh
 	@echo 'set -e' >> $(BUILD_DIR)/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-$(GOOS)-$(GOARCH)/install.sh