[llvm-branch-commits] [BOLT] Allow builtin_unreachable to be at MaxSize address (PR #111771)

[Amir Ayupov via llvm-branch-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/111771

Lift the restriction that builtin_unreachable has to be strictly within
`MaxSize` of a function.

Test Plan: added builtin_unreachable.s