Fixed Lua 5.1 compatibility with lua_len() and cleaned up makefile so it

doesn't test by default.

Makefile

@@ -4,7 +4,7 @@
 LUAINC= $(LUA)/src
 LUALIB= $(LUA)/src
 LUABIN= $(LUA)/src
-LUASUFFIX= ""
+LUASUFFIX= 
 
 # these will probably work if Lua has been installed globally
 #LUA= /usr/local
@@ -26,9 +26,9 @@ T= $(MYNAME).so
 OBJS= $(MYLIB).o
 TEST= test.lua
 
-all:	test
+all: $T
 
-test:	$T
+test: $T
 	$(LUABIN)/lua$(LUASUFFIX) $(TEST)
 
 o:	$(MYLIB).o

limmutable.c

@@ -207,7 +207,7 @@ static int Llen(lua_State *L)
     // Stack: [mt]
     lua_getfield(L, -1, "__fields");
     // Stack: [mt, fields]
-    lua_len(L, -1);
+    lua_pushinteger(L, lua_objlen(L, -1));
     return 1;
 }