Download qemu-arm-static from the multiarch project

This avoids importing it from the gitlab-runner system.

.gitignore

@@ -4,3 +4,4 @@
 
 # artifacts
 *.tar*
+/qemu*

Makefile

@@ -11,6 +11,10 @@ endif
 FROM := $(shell grep FROM Dockerfile | cut -d" " -f2)
 IMAGE := $(IMAGE_PREFIX)debootstrap
 
+QEMU_VERSION = v3.1.0-2
+QEMU_STATIC = https://github.com/multiarch/qemu-user-static/releases/download/$(QEMU_VERSION)/qemu-arm-static.tar.gz
+QEMU_CHECKSUM = 694df07f3d83b64b2e3598f3150046e7c6c4f5f15004a4f2f414caf8e719bdcefe3fc8a8fa1f5cff357aa6af1a018a4e9efdc287a491037b89aa47aeaefb2201
+
 .PHONY: all clean build
 
 all: pull build
@@ -19,8 +23,13 @@ pull:
 	docker pull "$(IMAGE)" || true
 	docker pull "$(FROM)"
 
-build:
-	cp -av /usr/bin/qemu-arm-static .
+qemu-arm-static:
+	wget "$(QEMU_STATIC)" -O $@.tar.gz
+	echo "$(QEMU_CHECKSUM) $@.tar.gz" | sha512sum -c - || (sha512sum $@.tar.gz; false)
+	tar xf $@.tar.gz
+	rm -f $@.tar.gz
+
+build: qemu-arm-static
 	docker build --cache-from "$(IMAGE)" --tag "$(IMAGE)" .
 
 push: