patch 8.2.2559: MS-Windows: guifont test fails on Windows XP

Problem:    MS-Windows: guifont test fails on Windows XP.
Solution:   Check windowsversion().

src/testdir/test_gui.vim

@@ -388,7 +388,9 @@ func Test_set_guifont()
     call assert_fails('set guifont=xa1bc23d7f', 'E596:')
   endif
 
-  if exists('+renderoptions')
+  " This only works if 'renderoptions' exists and does not work for Windows XP
+  " and older. 
+  if exists('+renderoptions') && windowsversion() !~ '^[345]\.'
     " doing this four times used to cause a crash
     set renderoptions=type:directx
     for i in range(5)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2559,
 /**/
     2558,
 /**/