patch 9.1.1238: wrong cursor column with 'set splitkeep=screen'

patch 9.1.1238: wrong cursor column with 'set splitkeep=screen'

Problem:  With ':set splitkeep=screen', cursor did't restore column
          correctly when splitting a window on a line longer than the
          last line on the screen (after v9.1.0707)
Solution: Restore cursor column in `win_fix_scroll()` since it may be
          changed in `getvcol()` after 396fd1ec2956 (phanium).

Example:
```
echo longlonglongling\nshort | vim - -u NONE --cmd 'set
splitkeep=screen' +'norm $' +new +q
```

fixes: #16968
closes: #16971

Signed-off-by: phanium <91544758+phanen@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>