Add GC stub, let1
diff --git a/src/lisp/gc.h b/src/lisp/gc.h
new file mode 100644
index 0000000..da5982a
--- /dev/null
+++ b/src/lisp/gc.h
@@ -0,0 +1,5 @@
+#pragma once
+
+void _do_gc(unsigned int esp, unsigned int ebp);
+void _mark(unsigned int value);
+void _sweep();