tests/docker: remove debian-powerpc-user-cross

Despite our attempts in 4d26c7fef4 to keep this going it still gets in
the way of "make docker-test-build" completing because of course we
can't build a modern QEMU with the image. Let's put the thing out of
its misery and remove it.

People who really care about building on powerpc can still use the
binfmt_misc support to manually build an image (or just run the build
from pre this commit).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

tests/docker/Makefile.include

@@ -147,15 +147,6 @@ DOCKER_PARTIAL_IMAGES += fedora-i386-cross fedora-cris-cross
 # work around issues with poorly working multi-arch systems and broken
 # packages.
 
-# Jessie is the last supported release for powerpc, but multi-arch is
-# broken so we need a qemu-linux-user for this target
-docker-binfmt-image-debian-powerpc-user: DEB_ARCH = powerpc
-docker-binfmt-image-debian-powerpc-user: DEB_TYPE = jessie
-docker-binfmt-image-debian-powerpc-user: DEB_URL = http://snapshot.debian.org/archive/debian/20180615T211437Z
-docker-binfmt-image-debian-powerpc-user: EXECUTABLE = ${BUILD_DIR}/ppc-linux-user/qemu-ppc
-docker-image-debian-powerpc-user-cross: docker-binfmt-image-debian-powerpc-user
-DOCKER_USER_IMAGES += debian-powerpc-user
-
 # Expand all the pre-requistes for each docker image and test combination
 $(foreach i,$(filter-out $(DOCKER_PARTIAL_IMAGES),$(DOCKER_IMAGES)), \
 	$(foreach t,$(DOCKER_TESTS) $(DOCKER_TOOLS), \

tests/docker/dockerfiles/debian-powerpc-user-cross.docker

@@ -1,21 +0,0 @@
-#
-# Docker powerpc cross-compiler target for QEMU
-#
-# We can't use current Debian stable cross-compilers to build powerpc
-# as it has been dropped as a release architecture. Using Debian Sid
-# is just far too sketchy a build environment. This leaves us the
-# final option of using linux-user. This image is based of the
-# debootstrapped qemu:debian-powerpc-user but doesn't need any extra
-# magic once it is setup.
-#
-# It can be used to build old versions of QEMU, current versions need
-# newer dependencies than Jessie provides.
-#
-FROM qemu:debian-powerpc-user
-
-RUN echo man-db man-db/auto-update boolean false | debconf-set-selections
-RUN apt-get update && \
-        DEBIAN_FRONTEND=noninteractive apt-get build-dep -yy qemu
-
-ENV QEMU_CONFIGURE_OPTS --disable-werror
-ENV DEF_TARGET_LIST powerpc-softmmu,arm-linux-user,aarch64-linux-user