tests: Allow overriding archive path with SRC_ARCHIVE

In VM based tests, the source archive is created in host, we don't have
to run archive-source.sh again, as it complicates the Makefile and
scripts.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-Id: <20180712012829.20231-4-famz@redhat.com>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NFam Zheng <famz@redhat.com>

tests/docker/Makefile.include

@@ -27,8 +27,11 @@ DOCKER_SRC_COPY := $(BUILD_DIR)/docker-src.$(CUR_TIME)
 
 $(DOCKER_SRC_COPY):
 	@mkdir $@
-	$(call quiet-command, cd $(SRC_PATH) && scripts/archive-source.sh $@/qemu.tar, \
-		"GEN", "$@/qemu.tar")
+	$(if $(SRC_ARCHIVE), \
+		$(call quiet-command, cp "$(SRC_ARCHIVE)" $@/qemu.tar, \
+			"CP", "$@/qemu.tar"), \
+		$(call quiet-command, cd $(SRC_PATH) && scripts/archive-source.sh $@/qemu.tar, \
+			"GEN", "$@/qemu.tar"))
 	$(call quiet-command, cp $(SRC_PATH)/tests/docker/run $@/run, \
 		"COPY","RUNNER")