worktree: prepare for more checks of whether path can become worktree

diff --git a/trailer.h b/trailer.h
index 6d7f8c2a52305d3d937b69a877f1ae0b7af94363..9c10026c358326ce0c0098ca52341ce8160c5bbe 100644 (file)
--- a/trailer.h
+++ b/trailer.h
@@ -3,6 +3,8 @@
 
 #include "list.h"
 
+struct strbuf;
+
 enum trailer_where {
        WHERE_DEFAULT,
        WHERE_END,