patch 8.0.0810: MS-Windows: tests still hang

Problem:    MS-Windows: tests still hang.
Solution:   Only create the XfakeHOME directory if it does not exist yet.

src/testdir/setup.vim

@@ -24,5 +24,7 @@ if 1
   " Make sure $HOME does not get read or written.
   " It must exist, gnome tries to create $HOME/.gnome2
   let $HOME = getcwd() . '/XfakeHOME'
+  if !isdirectory($HOME)
     call mkdir($HOME)
   endif
+endif

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    810,
 /**/
     809,
 /**/