Replace TOY_LIST_LEN with more generic ARRAY_LEN()
diff --git a/toys.h b/toys.h
index a03ed7c..0338077 100644
--- a/toys.h
+++ b/toys.h
@@ -108,3 +108,5 @@
 extern char toybuf[4096];
 
 #define DEFINE_GLOBALS(...)
+
+#define ARRAY_LEN(array) (sizeof(array)/sizeof(*array))