Encoding of table indices (hres) must use C indices

As the encoding of array indices is (~index), 0 is encoded as -1 and
INT_MAX is encoded as INT_MIN.

lvm.c

@@ -1857,7 +1857,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
           luaH_resizearray(L, h, last);  /* preallocate it at once */
         for (; n > 0; n--) {
           TValue *val = s2v(ra + n);
-          obj2arr(h, last, val);
+          obj2arr(h, last - 1, val);
           last--;
           luaC_barrierback(L, obj2gco(h), val);
         }