rust-bootstrap: attempts to build universal, but the latter no longer supported by cmake-bootstrap

[mascguy (Christopher Nielsen)]

It's not clear whether this is an issue with rust-bootstrap, cmake-bootstrap, or both. But the former enables +universal by default, whilst the latter no longer supports universal builds as of 2023-06:

​https://github.com/macports/macports-ports/commit/a4fda7b98703ff055b9dacb7e1dca58d5376d490

Perhaps that's fine though...?

However, the build for rust-bootstrap is blocked, due to cmake-bootstrap failing to build:

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CMake 3.9.6, Copyright 2000-2017 Kitware, Inc. and Contributors
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Error when bootstrapping CMake:
Cannot find appropriate C compiler on this system.
Please specify one using environment variable CC.
See cmake_bootstrap.log for compilers attempted.

​https://build.macports.org/builders/ports-13_arm64-builder/builds/32652/steps/install-dependencies/logs/stdio

Full log also attached: cmake-bootstrap-build-13-arm.log.gz.