Allow more flexible config

Author: sapk

Makefile

@@ -140,20 +140,20 @@ docker-multi-build: docker-multi-setenv
 
 .PHONY: docker-multi-amd64
 docker-multi-amd64: GITEA_VERSION ?= "master"
-docker-multi-amd64: DOCKER_BASE=alpine:latest
-docker-multi-amd64: DOCKER_TAG=linux-amd64-$(GITEA_VERSION)
+docker-multi-amd64: DOCKER_BASE ?= alpine:latest
+docker-multi-amd64: DOCKER_TAG ?= linux-amd64-$(GITEA_VERSION)
 docker-multi-amd64: docker-multi-build
 
 .PHONY: docker-multi-arm
 docker-multi-arm: GITEA_VERSION ?= "master"
-docker-multi-arm: DOCKER_BASE=multiarch/alpine:armhf-latest-stable
-docker-multi-arm: DOCKER_TAG=linux-arm-$(GITEA_VERSION)
+docker-multi-arm: DOCKER_BASE ?= multiarch/alpine:armhf-latest-stable
+docker-multi-arm: DOCKER_TAG ?= linux-arm-$(GITEA_VERSION)
 docker-multi-arm: docker-multi-build
 
 .PHONY: docker-multi-arm64
 docker-multi-arm64: GITEA_VERSION ?= "master"
-docker-multi-arm64: DOCKER_BASE=multiarch/alpine:aarch64-latest-stable
-docker-multi-arm64: DOCKER_TAG=linux-arm64-$(GITEA_VERSION)
+docker-multi-arm64: DOCKER_BASE ?= multiarch/alpine:aarch64-latest-stable
+docker-multi-arm64: DOCKER_TAG ?= linux-arm64-$(GITEA_VERSION)
 docker-multi-arm64: docker-multi-build
 
 .PHONY: docker-multi-push