Bug 1684110 - Stop using some 'A'-functions in widget/windows/. r=mhowell

Depends on D100468

Differential Revision: https://phabricator.services.mozilla.com/D100469

widget/windows/tests/TestUriValidation.cpp

@@ -6,6 +6,7 @@
 
 #define MOZ_USE_LAUNCHER_ERROR
 
+#define UNICODE
 #include "mozilla/UrlmonHeaderOnlyUtils.h"
 #include "TestUrisToValidate.h"