patch 9.0.1277: cursor may move with autocmd in Visual mode

Problem:    Cursor may move with autocmd in Visual mode.
Solution:   Restore "VIsual_active" before calling check_cursor().
            (closes #11939)
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 99403e2..3bea88d 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1648,7 +1648,7 @@
 
 func Test_setbufvar_options()
   " This tests that aucmd_prepbuf() and aucmd_restbuf() properly restore the
-  " window layout.
+  " window layout and cursor position.
   call assert_equal(1, winnr('$'))
   split dummy_preview
   resize 2
@@ -1662,11 +1662,20 @@
   execute 'belowright vertical split #' . dummy_buf
   call assert_equal(wh, winheight(0))
   let dum1_id = win_getid()
+  call setline(1, 'foo')
+  normal! V$
+  call assert_equal(4, col('.'))
+  call setbufvar('dummy_preview', '&buftype', 'nofile')
+  call assert_equal(4, col('.'))
 
   wincmd h
   let wh = winheight(0)
+  call setline(1, 'foo')
+  normal! V$
+  call assert_equal(4, col('.'))
   let dummy_buf = bufnr('dummy_buf2', v:true)
   eval 'nofile'->setbufvar(dummy_buf, '&buftype')
+  call assert_equal(4, col('.'))
   execute 'belowright vertical split #' . dummy_buf
   call assert_equal(wh, winheight(0))