patch 8.1.1482: no test for wincol() depending on the 'number' option

Problem:    No test for wincol() depending on the 'number' option.
Solution:   Add a couple of tests. (Christian Brabandt, closes #4500)
diff --git a/src/testdir/test_gui.vim b/src/testdir/test_gui.vim
index a372c1f..5a1763d 100644
--- a/src/testdir/test_gui.vim
+++ b/src/testdir/test_gui.vim
@@ -694,12 +694,22 @@
   call setline(11, repeat('x', 150))
   redraw
   call assert_equal(1, wincol())
+  set number
+  redraw
+  call assert_equal(5, wincol())
+  set nonumber
+  redraw
   call assert_equal(1, col('.'))
 
   " scroll to character 11, cursor is moved
   call test_scrollbar('hor', 10, 0)
   redraw
   call assert_equal(1, wincol())
+  set number
+  redraw
+  call assert_equal(5, wincol())
+  set nonumber
+  redraw
   call assert_equal(11, col('.'))
 
   set guioptions&