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/i386/tcg-target.c

@@ -77,6 +77,11 @@ static const int tcg_target_call_iarg_regs[] = {
     TCG_REG_R8,
     TCG_REG_R9,
 #else
+#ifdef _MSC_VER
+#ifdef _UC_MSVC_ARRAY_DUMMY
+#error "DUP DEF _UC_MSVC_ARRAY_DUMMY"
+#endif
+#define _UC_MSVC_ARRAY_DUMMY
     /* 32 bit mode uses stack based calling convention (GCC default).
     We add a dummy value here for MSVC compatibility for the error:
     "error C2466: cannot allocate an array of constant size 0"
@@ -85,6 +90,7 @@ static const int tcg_target_call_iarg_regs[] = {
     */
     0,
 #endif
+#endif
 };
 
 static const int tcg_target_call_oarg_regs[] = {