New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/23601#issuecomment-661299884

Comment:
Now that I'm thinking about this again, I wonder if looking at the basename is the right choice. Maybe it should just compare `${file#$PKGDESTDIR}` to the contents of `$ignore_usrshare_files` so we can differentiate files like
```
/usr/share/elf-allowed/myfile
/usr/share/elf-bad/myfile
```
The same should probably hold with `$ignore_usrshare_dirs`: require the full path (wrt `$PKGDESTDIR`) be specified instead of just the basename.