urlview: fix path to url_handler.sh
urlview: fix path to url_handler.sh

By default, `/etc/urlview/url_handler.sh` is used which breaks by
default with the following error:

```
sh: /etc/urlview/url_handler.sh: No such file or directory
```

With this change, the script will be copied to `$out` and `urlview` will
be patched accordingly.

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