btrfs-progs: ci: add helpers to update base images

Add convenience build scripts for updating all CI images.

    $ images-base-update
    $ images-build-all

Signed-off-by: David Sterba <dsterba@suse.com>

ci/images/images-base-update

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# Update all base images from Dockefile
+for dir in ci-*; do
+	echo "Update $dir"
+	cd "$dir"
+	docker pull `awk '/^FROM/ {print $$2}' < Dockerfile`
+	cd ..
+done

ci/images/images-build-all

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# Rebuild all docker images
+for dir in ci-*; do
+	echo "Build $dir"
+	cd "$dir"
+	./docker-build
+	cd ..
+done