x64: Fix result type of cdata index conversions.

src/lj_opt_narrow.c

@@ -495,7 +495,7 @@ TRef LJ_FASTCALL lj_opt_narrow_cindex(jit_State *J, TRef tr)
 {
   lua_assert(tref_isnumber(tr));
   if (tref_isnum(tr))
-    return emitir(IRTI(IR_CONV), tr,
+    return emitir(IRT(IR_CONV, IRT_INTP), tr,
 		  (IRT_INTP<<5)|IRT_NUM|IRCONV_TRUNC|IRCONV_ANY);
   /* Undefined overflow semantics allow stripping of ADDOV, SUBOV and MULOV. */
   return narrow_stripov(J, tr, IR_MULOV,