Reduce minimum Lua frame size to 1.

src/lj_parse.c

@@ -1233,7 +1233,7 @@ static void fs_init(LexState *ls, FuncState *fs)
   fs->nuv = 0;
   fs->bl = NULL;
   fs->flags = 0;
-  fs->framesize = 2;  /* Minimum frame size. */
+  fs->framesize = 1;  /* Minimum frame size. */
   fs->kt = lj_tab_new(L, 0, 0);
   /* Anchor table of constants in stack to avoid being collected. */
   settabV(L, L->top, fs->kt);