patch 8.2.5145: exit test causes spurious valgrind reports

Problem:    Exit test causes spurious valgrind reports.
Solution:   Skip test.  Add CheckNotValgrind.
diff --git a/src/testdir/test_exit.vim b/src/testdir/test_exit.vim
index c05374c..a7596e1 100644
--- a/src/testdir/test_exit.vim
+++ b/src/testdir/test_exit.vim
@@ -115,6 +115,7 @@
   CheckNotMSWindows
   " The early exit causes memory not to be freed somehow
   CheckNotAsan
+  CheckNotValgrind
 
   call writefile([":au VimLeave * call writefile(['l = ' .. v:exiting], 'Xtestout')", ":tabnew", "q:"], 'Xscript', 'b')