Auto merge of #133369 - Zalathar:profiler-builtins-no-core, r=jieyouxu

Allow injecting a profiler runtime into `#![no_core]` crates

An alternative to #133300, allowing `-Cinstrument-coverage` to be used with `-Zbuild-std`.

The incompatibility between `profiler_builtins` and `#![no_core]` crates appears to have been caused by profiler_builtins depending on core, and therefore conflicting with core (or minicore).

But that's a false dependency, because the profiler doesn't contain any actual Rust code. So we can just mark the profiler itself as `#![no_core]`, and remove the incompatibility error.

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For context, the error was originally added by #79958.

Author: bors