Clock component removed from 'luaL_makeseed'

'clock' can be quite slow on some machines.

ltablib.c

@@ -310,7 +310,7 @@ static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
 */
 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
   IdxT r4 = (up - lo) / 4;  /* range/4 */
-  IdxT p = rnd % (r4 * 2) + (lo + r4);
+  IdxT p = (rnd ^ lo ^ up) % (r4 * 2) + (lo + r4);
   lua_assert(lo + r4 <= p && p <= up - r4);
   return p;
 }