Add submodules to build/packages

Using symlinks the submodules are added to appear just like any
downloaded unpacked tar.

Also added a Makefile clean rule to clean the submodules, which
includes Reseting the submodules to the origin branch state,
including ignored files.

Makefile

@@ -1,6 +1,8 @@
 ARCHS := x86_64 arm aarch64 powerpc mips mipsel
 TARGETS := $(addprefix build-, $(ARCHS))
 PACK_TARGETS := $(addprefix pack-, $(ARCHS))
+SUBMODULE_PACKAGES := $(wildcard src/submodule_packages/*)
+BUILD_PACKAGES_DIR := "build/packages"
 
 .PHONY: clean help download_packages build build-docker-image $(TARGETS) $(PACK_TARGETS)
 
@@ -23,22 +25,28 @@ build/build-docker-image.stamp: Dockerfile
 
 build-docker-image: build/build-docker-image.stamp
 
-build/download-packages.stamp: build/build-docker-image.stamp src/download_packages.sh
-	mkdir -p build/packages
+build/download-packages.stamp: build/build-docker-image.stamp src/compilation/download_packages.sh
+	mkdir -p $(BUILD_PACKAGES_DIR)
 	docker run --user $(shell id -u):$(shell id -g) \
 		--rm --volume .:/app/gdb gdb-static env TERM=xterm-256color \
-		/app/gdb/src/download_packages.sh /app/gdb/build/packages
+		/app/gdb/src/compilation/download_packages.sh /app/gdb/$(BUILD_PACKAGES_DIR)/
 	touch build/download-packages.stamp
 
+build/symlink-git-packages.stamp: $(SUBMODULE_PACKAGES)
+	mkdir -p $(BUILD_PACKAGES_DIR)
+	ln -sf $(addprefix /app/gdb/, $(SUBMODULE_PACKAGES)) $(BUILD_PACKAGES_DIR)/
+
+symlink-git-packages: build/symlink-git-packages.stamp
+
 download-packages: build/download-packages.stamp
 
 build: $(TARGETS)
 
-$(TARGETS): build-%: download-packages build-docker-image
+$(TARGETS): build-%: symlink-git-packages download-packages build-docker-image
 	mkdir -p build
 	docker run --user $(shell id -u):$(shell id -g) \
 		--rm --volume .:/app/gdb gdb-static env TERM=xterm-256color \
-		/app/gdb/src/build.sh $* /app/gdb/build/ /app/gdb/src
+		/app/gdb/src/compilation/build.sh $* /app/gdb/build/ /app/gdb/src
 
 pack: $(PACK_TARGETS)
 
@@ -47,7 +55,10 @@ $(PACK_TARGETS): pack-%: build-%
 		tar -czf "build/artifacts/gdb-static-$*.tar.gz" -C "build/artifacts/$*" .; \
 	fi
 
-clean:
+clean-git-packages:
+	git submodule foreach '[[ ! "$$sm_path" == src/submodule_packages/* ]] || git clean -xffd'
+
+clean: clean-git-packages
 	rm -rf build
 # Kill and remove all containers of image gdb-static
 	docker ps -a | grep -P "^[a-f0-9]+\s+gdb-static\s+" | awk '{print $$1}' | xargs docker rm -f 2>/dev/null || true