Update to the latest stable Debian. While we are at it flatten into a
single dockerfile. We really don't need the rest of the stuff from the
QEMU base image just to compile test images. In this case it is a
binary distribution of the toolchain anyway.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220914155950.804707-27-alex.bennee@linaro.org>
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