arch/sim/wchar_t: fix visual studio Compiler Error C2371
type of 'wchar_t' confilt with vcruntime:
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.33.31629\include\vcruntime.h(228,28):
error C2371: 'wchar_t': redefinition; different basic types
D:\code\incubator-nuttx\include\sys/types.h(174): message : see decaration of 'wchar_t'
typedef wchar_t as unsigned char to compatible with vcrtuntime
@@ -88,6 +88,8 @@ typedef _uint64_t _uintmax_t;
#if defined(__WCHAR_TYPE__)
typedef __WCHAR_TYPE__ _wchar_t;
+#elif defined(_MSC_VER)
+typedef unsigned short _wchar_t;
#else
typedef int _wchar_t;
#endif
