[llvm] [BOLT][AArch64] Remove thunk estimation and warn on margin exhaustion (PR #228069)

[Alexandros Lamprineas via llvm-commits]

https://github.com/labrinea created https://github.com/llvm/llvm-project/pull/228069

When performing branch range checks compare modeled hop distances with MaxClusterSize inclusively without charging estimated thunk bytes against it. This allows a thunk at an adjacent cluster boundary to reach its target.

Cap MaxClusterSize at 126 MiB to reserve minimum alignment headroom. Warn when thunk bytes plus text alignment exceed the remaining branch safety margin.

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