patch 8.2.4967: MS-Windows GUI: mouse event test sometimes fails

Problem:    MS-Windows GUI: mouse event test sometimes fails.
Solution:   Ignore one move event only if there is an extra event.
diff --git a/src/testdir/test_gui.vim b/src/testdir/test_gui.vim
index 5561d84..2c08340 100644
--- a/src/testdir/test_gui.vim
+++ b/src/testdir/test_gui.vim
@@ -1252,8 +1252,8 @@
   call test_gui_event('mouse', args)
   call feedkeys('', 'Lx!')
 
-  if has('win32')
-    " FIXME: on MS-Windows we get a stray event first
+  " FIXME: on MS-Windows we get a stray event first
+  if has('win32') && len(g:eventlist) == 3
     let g:eventlist = g:eventlist[1 : ]
   endif