packbuilder: use git__noop on non-threaded systems Our git_packbuilder__cache_lock function returns a value; use git__noop.
diff --git a/src/pack-objects.c b/src/pack-objects.c
index 8ebb8cf..03d05b7 100644
--- a/src/pack-objects.c
+++ b/src/pack-objects.c
@@ -50,7 +50,7 @@ struct walk_object {
#ifdef GIT_THREADS
# define GIT_PACKBUILDER__MUTEX_OP(pb, mtx, op) git_mutex_##op(&(pb)->mtx)
#else
-# define GIT_PACKBUILDER__MUTEX_OP(pb, mtx, op) GIT_UNUSED(pb)
+# define GIT_PACKBUILDER__MUTEX_OP(pb, mtx, op) git__noop()
#endif
#define git_packbuilder__cache_lock(pb) GIT_PACKBUILDER__MUTEX_OP(pb, cache_mutex, lock)