docker: reduce image size a bit

Removes source and objects for qemu and linux kernel, packer cache, and
raw images.

docker/Dockerfile

@@ -2,7 +2,7 @@ FROM simbricks-build AS simbricks-obj
 COPY . /simbricks
 WORKDIR /simbricks
 RUN make -j `nproc` ENABLE_VERILATOR=y
-RUN make -j `nproc` sims/external/qemu/ready
+RUN make -j `nproc` sims/external/qemu/ready \
+ && bash docker/cleanup_external.sh
 RUN make -j `nproc` build-images-min COMPRESSED_IMAGES=true \
-	&& rm -f images/output-*/*.raw
-
+ && bash docker/cleanup_images.sh

docker/cleanup_external.sh

+#!/bin/bash
+set -e
+mkdir -p sims/external/qemu-new/build/x86_64-softmmu/
+rm -rf sims/external/qemu/build/pc-bios/{edk2-aarch64*,edk2-arm*}
+mv sims/external/qemu/build/{qemu-img,qemu-system-x86_64,pc-bios} \
+	sims/external/qemu-new/build/
+mv sims/external/qemu/pc-bios/ \
+	sims/external/qemu-new/
+rm -rf sims/external/qemu
+mv sims/external/qemu-new sims/external/qemu
+ln -s /simbricks/sims/external/qemu/build/qemu-system-x86_64 \
+	sims/external/qemu/build/x86_64-softmmu/qemu-system-x86_64
+touch sims/external/qemu/ready

docker/cleanup_images.sh

+#!/bin/bash
+set -e
+rm -rf images/{packer,packer_cache}
+rm -rf images/output-*/*.raw
+rm -rf images/kernel/{kheaders,linux-5.4.46}