[AllocToken] Refactor stateless token calculation into Support (#163633)

Refactor the stateless (hash-based) token calculation logic out of the
`AllocToken` pass and into `llvm/Support/AllocToken.h`.

This helps with making the token calculation logic available to other
parts of the codebase, which will be necessary for frontend
implementation of `__builtin_infer_alloc_token` to perform constexpr
evaluation.

The `AllocTokenMode` enum and a new `AllocTokenMetadata` struct are
moved into a shared header. The `getAllocTokenHash()` function now
provides the source of truth for calculating token IDs for `TypeHash`
and `TypeHashPointerSplit` modes.

0 files changed, 0 insertions, 0 deletions