ucrtbase: Let stderr be always be unbuffered.

dlls/msvcrt/file.c

@@ -830,9 +830,15 @@ int CDECL _isatty(int fd)
 /* INTERNAL: Allocate stdio file buffer */
 static BOOL msvcrt_alloc_buffer(FILE* file)
 {
+#if _MSVCR_VER >= 140
+    if((file->_file==STDOUT_FILENO && _isatty(file->_file))
+        || file->_file == STDERR_FILENO)
+        return FALSE;
+#else
     if((file->_file==STDOUT_FILENO || file->_file==STDERR_FILENO)
             && _isatty(file->_file))
         return FALSE;
+#endif
 
     file->_base = calloc(1, MSVCRT_INTERNAL_BUFSIZ);
     if(file->_base) {

dlls/ucrtbase/tests/file.c

@@ -55,7 +55,6 @@ static void test_std_stream_buffering(void)
     if (broken(!GetProcAddress(GetModuleHandleA("ucrtbase"), "__CxxFrameHandler4") && !pos))
         trace("stderr is buffered\n");
     else
-        todo_wine
         ok(pos == 4, "expected stderr to be unbuffered (%d)\n", pos);
 
     fflush(stderr);