get std.typecons to compile with PR #14364

[WalterBright]

blocking dlang/dmd#14364

[dlang-bot]

Thanks for your pull request, @WalterBright!

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#8533"

[WalterBright]

logger strikes again:

****** FAIL release32 std.logger.core
core.exception.AssertError@std/logger/core.d(1900): unittest failure

I increased the priority of https://issues.dlang.org/show_bug.cgi?id=23286

[thewilsonator]

Aren't unit tests supposed to be explicitly marked either @safe or @system?