Fix wxBase compilation with UTF-8-based wxString under MSW.

Use wxString::t_str() instead of wx_str() in Windows API function calls.

Closes #14325.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71546 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/strvararg.cpp

@@ -435,6 +435,8 @@ class wxPrintfFormatConverterWchar : public wxFormatConverterBase<wchar_t>
 };
 #endif // !wxUSE_UTF8_LOCALE_ONLY
 
+#endif // __WINDOWS__/!__WINDOWS__
+
 #if wxUSE_UNICODE_UTF8
 class wxPrintfFormatConverterUtf8 : public wxFormatConverterBase<char>
 {
@@ -458,8 +460,6 @@ class wxPrintfFormatConverterUtf8 : public wxFormatConverterBase<char>
 };
 #endif // wxUSE_UNICODE_UTF8
 
-#endif // __WINDOWS__/!__WINDOWS__
-
 #if !wxUSE_UNICODE // FIXME-UTF8: remove
 class wxPrintfFormatConverterANSI : public wxFormatConverterBase<char>
 {