Flag for to-be-closed variables changed to '<toclose>'

The flag for to-be-closed variables was changed from '*toclose'
to '<toclose>'. Several people found confusing the old syntax and
the new one has a clear terminator, making it more flexible for
future changes.

testes/goto.lua

@@ -258,7 +258,7 @@ do
   ::L2:: goto L3
 
   ::L1:: do
-    local *toclose a = setmetatable({}, {__close = function () X = true end})
+    local <toclose> a = setmetatable({}, {__close = function () X = true end})
     assert(X == nil)
     if a then goto L2 end   -- jumping back out of scope of 'a'
   end