helper/options: handle errors in `-l`

Before the patch an error in opening the log file (e.g. can't write a
file) was ignored when specified via `-l`.
E.g.:
```
> touch log
> chmod -w log
> openocd -l log -c shutdown
...
failed to open output log "log"
shutdown command invoked
> echo $?
0
```

After the patch:
```
...
> openocd -l log -c shutdown
...
failed to open output log "log"
> echo $?
1
```

Change-Id: Ibab45f580dc46a499bf967c4afad071f9c2972a2
Signed-off-by: Evgeniy Naydanov <evgeniy.naydanov@syntacore.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8666
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

0 files changed, 0 insertions, 0 deletions