patch 8.1.1184: undo file left behind after running test

Problem:    Undo file left behind after running test.
Solution:   Delete the undo file. (Dominique Pelle, closes #4279)

src/testdir/test_filechanged.vim

@@ -86,6 +86,7 @@ func Test_FileChangedShell_reload()
 
   au! testreload
   bwipe!
+  call delete(undofile('Xchanged_r'))
   call delete('Xchanged_r')
 endfunc
 

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1184,
 /**/
     1183,
 /**/