patch 8.1.0212: preferred cursor column not set in interfaces

Problem:    Preferred cursor column not set in interfaces.
Solution:   Set w_set_curswant when setting the cursor. (David Hotham,
            closes #3060)
diff --git a/src/testdir/test_ruby.vim b/src/testdir/test_ruby.vim
index 0017f73..ae27b39 100644
--- a/src/testdir/test_ruby.vim
+++ b/src/testdir/test_ruby.vim
@@ -57,3 +57,16 @@
   call assert_fails('rubyfile ' . tempfile)
   call delete(tempfile)
 endfunc
+
+func Test_set_cursor()
+  " Check that setting the cursor position works.
+  new
+  call setline(1, ['first line', 'second line'])
+  normal gg
+  rubydo $curwin.cursor = [1, 5]
+  call assert_equal([1, 6], [line('.'), col('.')])
+
+  " Check that movement after setting cursor position keeps current column.
+  normal j
+  call assert_equal([2, 6], [line('.'), col('.')])
+endfunc