patch 8.2.0763: GUI test fails without the terminal feature

Problem:    GUI test fails without the terminal feature.
Solution:   Check the terminal feature is supported. (Ken Takata,
            closes #6084)

src/testdir/test_gui.vim

@@ -841,6 +841,7 @@ endfunc
 " Test for "!" option in 'guioptions'. Use a terminal for running external
 " commands
 func Test_gui_run_cmd_in_terminal()
+  CheckFeature terminal
   let save_guioptions = &guioptions
   set guioptions+=!
   if has('win32')

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    763,
 /**/
     762,
 /**/