New comment by HiPhish on void-packages repository

https://github.com/void-linux/void-packages/issues/48303#issuecomment-1902219826

Comment:
Updating xlint would be good, but if we want to support more complex expressions that involve parentheses it gets much more complicated. One solution would be to internally ignore any parentheses, then we only validate the individual license identifiers, but not the entire expression. Or we shell out to a dedicated validator.

And the manual should be updated to recommend SPDX expressions instead of comma.