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)

src/if_perl.xs

@@ -1691,6 +1691,7 @@ Cursor(win, ...)
       col = (int) SvIV(ST(2));
       win->w_cursor.lnum = lnum;
       win->w_cursor.col = col;
+      win->w_set_curswant = TRUE;
       check_cursor();		    /* put cursor on an existing line */
       update_screen(NOT_VALID);
     }