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/if_ruby.c b/src/if_ruby.c
index d67801d..4b9af31 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -1517,6 +1517,7 @@
     col = RARRAY_PTR(pos)[1];
     win->w_cursor.lnum = NUM2LONG(lnum);
     win->w_cursor.col = NUM2UINT(col);
+    win->w_set_curswant = TRUE;
     check_cursor();		    /* put cursor on an existing line */
     update_screen(NOT_VALID);
     return Qnil;