patch 8.2.3742: dec mouse test fails without gnome terminfo entry

Problem:    Dec mouse test fails without gnome terminfo entry.
Solution:   Check if there is a gnome entry. Also fix 'acd' test on
            MS-Windows. (Dominique Pellé, closes #9282)
diff --git a/src/testdir/test_termcodes.vim b/src/testdir/test_termcodes.vim
index 887093c..614c097 100644
--- a/src/testdir/test_termcodes.vim
+++ b/src/testdir/test_termcodes.vim
@@ -2041,6 +2041,10 @@
 
 " Check that when DEC mouse codes are recognized a special key is handled.
 func Test_ignore_dec_mouse()
+  silent !infocmp gnome >/dev/null 2>&1
+  if v:shell_error != 0
+    throw 'Skipped: gnome entry missing in the terminfo db'
+  endif
 
   new
   let save_mouse = &mouse