Make ui-fulldeps/update-references executable

[etaoins]

When a ui-fulldeps comparison fails it suggests running update-references.sh:

src/test/ui-fulldeps/update-references.sh 'rust/build/x86_64-apple-darwin/test/ui-fulldeps' 'resolve-error.rs'

This does not work as update-references.sh isn't executable. The other update-references.sh in the ui directory is already executable so this looks like an oversight.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @aturon (or someone else) soon.

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[petrochenkov]

Ha, I created it on Windows, it worked there! :)

Thanks for the fix.
@bors r+ rollup

[bors]

📌 Commit 46c59ae has been approved by petrochenkov