docker: add simbricks/simbricks:gem5opt image

simbricks/simbricks additionally with gem5.opt installed in addition to
gem5.fast. About 1.1GB larger.

docker/Dockerfile.gem5opt

+FROM simbricks/simbricks:latest
+RUN mv sims/external/gem5 sims/external/gem5-old \
+ && git submodule update --init sims/external/gem5 \
+ && make -j `nproc` sims/external/gem5/ready GEM5_VARIANT=opt \
+ && mv sims/external/gem5/build/X86/gem5.opt \
+       sims/external/gem5-old/build/X86/gem5.opt \
+ && rm -rf sims/external/gem5 \
+ && mv sims/external/gem5-old sims/external/gem5

docker/rules.mk

@@ -36,6 +36,10 @@ docker-images:
 	docker build -t simbricks/simbricks-dist-worker:latest \
 		-f docker/Dockerfile.dist-worker docker
 
+docker-images-debug:
+	docker build -t simbricks/simbricks:gem5opt \
+		-f docker/Dockerfile.gem5opt docker
+
 docker-image-tofino:
 	docker build -t simbricks/simbricks:tofino \
 		-f docker/Dockerfile.tofino .