更新Makefile，增加make dep命令，只更新vendor/yunion.io/x/下的包

Makefile

@@ -3,7 +3,7 @@
 REPO_PREFIX := yunion.io/x/onecloud
 VENDOR_PATH := $(REPO_PREFIX)/vendor
 VERSION_PKG := $(VENDOR_PATH)/yunion.io/x/pkg/util/version
-ROOT_DIR := $(shell pwd)
+ROOT_DIR := $(CURDIR)
 BUILD_DIR := $(ROOT_DIR)/_output
 BIN_DIR := $(BUILD_DIR)/bin
 BUILD_SCRIPT := $(ROOT_DIR)/build/build.sh
@@ -95,5 +95,8 @@ fmt:
 	find . -type f -name "*.go" -not -path "./_output/*" \
 		-not -path "./vendor/*" | xargs gofmt -s -w
 
+dep:
+	cd $(ROOT_DIR) && dep ensure -v -update $(shell for p in $$(ls vendor/yunion.io/x/); do echo "yunion.io/x/$$p"; done | xargs)
+
 %:
 	@: