[PULL 02/31] tests/docker: all add DOCKER_BUILDKIT to RUNC environment

[Alex Bennée]

It seems we also need to pass DOCKER_BUILDKIT as an argument to docker
itself to get the full benefit of caching.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Suggested-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230315174331.2959-3-alex.bennee@linaro.org>

diff --git a/tests/docker/Makefile.include b/tests/docker/Makefile.include
index 54ed77f671..9401525325 100644
--- a/tests/docker/Makefile.include
+++ b/tests/docker/Makefile.include
@@ -39,7 +39,7 @@ docker-qemu-src: $(DOCKER_SRC_COPY)
 # General rule for building docker images.
 docker-image-%: $(DOCKER_FILES_DIR)/%.docker
          $(call quiet-command,                 \
-               $(RUNC) build                           \
+               DOCKER_BUILDKIT=1 $(RUNC) build         \
                $(if $V,,--quiet)                       \
                $(if $(NOCACHE),--no-cache,             \
                        $(if $(DOCKER_REGISTRY),--cache-from 
$(DOCKER_REGISTRY)/qemu/$*)) \
-- 
2.39.2