[llvm-branch-commits] [Clang][CodeGen] Introduce the AllocToken SanitizerKind (PR #162098)

[Marco Elver via llvm-branch-commits]

https://github.com/melver created https://github.com/llvm/llvm-project/pull/162098

Introduce the "alloc-token" sanitizer kind, in preparation of wiring it
up. Currently this is a no-op, and any attempt to enable it will result
in failure:

  clang: error: unsupported option '-fsanitize=alloc-token' for target 'x86_64-unknown-linux-gnu'

In this step we can already wire up the `sanitize_alloc_token` IR
attribute where the instrumentation is enabled. Subsequent changes will
complete wiring up the AllocToken pass.