4.0 | Make isset, unset and empty parenthesis owners

[jrfnl]

Repost from squizlabs/PHP_CodeSniffer#3118:

I was just wondering why isset(), unset() and empty() - all language constructs which require parentheses - are not considered parentheses owners.

Would it make sense to change that ? Should be a relatively easy change to make as far as I can see.

Happy to make the changes if there is interest.

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[Edit]: Might be useful to include exit(), die() and eval() as well, though these three don't require parentheses, but are "owners" when the parentheses are present.

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See the original post for some pointers about the implementation.