Extract collections benchmarks to libcollections/bench

[phungleson]

Good suggestion from @stjepang #39484 (comment)

r? @alexcrichton

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[ghost]

Thanks for the PR!

Just two concerns with this:

1. Naming the subdirectory "bench" instead of "benches" is inconsistent with Cargo's naming conventions - Cargo uses "tests" and "benches" rather than "test" and "bench".
2. Why do libcollectionstest and libcoretest live in their own directories rather than libcollections/test and libcore/test? Isn't that another consistency: having tests in their own directories but benches in subdirectories?

@alexcrichton Thoughts?

[bors]

☔ The latest upstream changes (presumably #39567) made this pull request unmergeable. Please resolve the merge conflicts.

[alexcrichton]

@stjepang yeah using benches and tests sounds good to me! The libcoretest/libcollectionstest are historical artifacts at this point (thank the makefiles), they can be moved whenever though now at this point!

[phungleson]

@alexcrichton @stjepang I have extracted to libcollections/benches and libcore/benches.

libcollections/tests and libcore/tests perhaps can be a PR after this.

[alexcrichton]

@bors: r+

Thanks!

[bors]

📌 Commit 7c8c45e has been approved by alexcrichton