patch 8.2.3969: value of MAXCOL not available in Vim script

Problem:    Value of MAXCOL not available in Vim script.
Solution:   Add v:maxcol. (Naohiro Ono, closes #9451)
diff --git a/src/testdir/test_cursor_func.vim b/src/testdir/test_cursor_func.vim
index b943059..965c704 100644
--- a/src/testdir/test_cursor_func.vim
+++ b/src/testdir/test_cursor_func.vim
@@ -38,6 +38,18 @@
   quit!
 endfunc
 
+func Test_curswant_maxcol()
+  new
+  call setline(1, 'foo')
+
+  " Test that after "$" command curswant is set to the same value as v:maxcol.
+  normal! 1G$
+  call assert_equal(v:maxcol, getcurpos()[4])
+  call assert_equal(v:maxcol, winsaveview().curswant)
+
+  quit!
+endfunc
+
 " Very short version of what matchparen does.
 function s:Highlight_Matching_Pair()
   let save_cursor = getcurpos()