ed25519 benchmarks

[franziskuskiefer]

Simple sign and verify benchmarks for ed25519 for https://github.com/hacl-star/hacl-star/pull/710.

[franziskuskiefer]

Do we measure hex-decoding + {sign, verfiy}? That should be fine to detect performance regressions? If we want to obtain numbers on sign and verify, maybe it would be better to already use a static uint8_t*? This would also reduce duplication of the message and key literals?

Not sure how Google Benchmark works. Does state.KeepRunning() signal the start of the measurement?

Nope, only the loop is measured.

[coveralls]

Pull Request Test Coverage Report for Build 3548464424

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 53.985%

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Totals
Change from base Build 3516015739:	0.0%
Covered Lines:	33230
Relevant Lines:	61554

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💛 - Coveralls