fix #1246 (#1254)

* fix finding python path which only has python3.

* fix #1246, arm host issue.

* skip assembler tests on non-x86 host.

* update macro of dummy value.

* fix MSVC macro.

* update dummy array value macro.

* restore to original qemu code.

qemu/tcg/optimize.c

@@ -574,9 +574,6 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
 
         /* Do copy propagation */
         for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
-            if (args[i] >= TCG_MAX_TEMPS) {
-                return NULL;
-            }
             if (temps[args[i]].state == TCG_TEMP_COPY) {
                 args[i] = find_better_copy(s, args[i]);
             }