tiny code refactoring in 'luaS_hash'

lstring.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.c,v 2.54 2015/10/08 15:53:31 roberto Exp roberto $
+** $Id: lstring.c,v 2.55 2015/11/03 15:36:01 roberto Exp roberto $
 ** String table (keeps all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -48,10 +48,9 @@ int luaS_eqlngstr (TString *a, TString *b) {
 
 unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
   unsigned int h = seed ^ cast(unsigned int, l);
-  size_t l1;
   size_t step = (l >> LUAI_HASHLIMIT) + 1;
-  for (l1 = l; l1 >= step; l1 -= step)
-    h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
+  for (; l >= step; l -= step)
+    h ^= ((h<<5) + (h>>2) + cast_byte(str[l - 1]));
   return h;
 }