dockerd: busybox compatibility

build hosts with busybox fail with long options on rm
command. Short versions are supported by all, so this
makes it script compatible with busybox hosts as well.

Signed-off-by: Oskari Rauta <oskari.rauta@gmail.com>

utils/dockerd/git-short-commit.sh

@@ -26,7 +26,7 @@ if [ -z "${GIT_DIR}" ]; then
 fi
 
 clean_up() {
-	rm --force --recursive "${GIT_DIR}"
+	rm -rf "${GIT_DIR}"
 }
 trap clean_up EXIT