patch 8.2.1941: Ex mode test fails on MS-Windows with GUI

Problem:    Ex mode test fails on MS-Windows with GUI.
Solution:   Skip the test when using gvim.
diff --git a/src/testdir/test_ex_mode.vim b/src/testdir/test_ex_mode.vim
index c9ec20e..8668763 100644
--- a/src/testdir/test_ex_mode.vim
+++ b/src/testdir/test_ex_mode.vim
@@ -181,6 +181,7 @@
 endfunc
 
 func Test_ex_mode_with_global()
+  CheckNotGui
   CheckFeature timers
 
   " This will get stuck in Normal mode after the failed "J", use a timer to