New review comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/23601#discussion_r455987384

Comment:
A test like
```
[[ ${ignore_in_usr_share} != *$(basename "$I")* ]]
```
to the match operator would be consistent with with match tests in the build-helpers.

Regardless, the argument to `basename` should be quoted in case the file has spaces in the name.

Also, why bother stripping out `PKGDESTDIR` from `file` if we are feeding it to basename anyway?