[llvm] [BOLT][AArch64] Patch functions targeted by optional relocs (PR #138750)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis approved this pull request.

Hey Maks,

Looks good, thanks! One thing to consider:

Given that `--compact-code-model` now avoids patching, it may be good to add a test for it.

As is, the test would fail as expected because its size requirement is not met.
However, with a decreased artificial gap in the hot section, we could verify that the cold_function (which remains in the original section) points directly to the hot section, without needing an indirection through the original `_start` (which should remain unpatched, ie not a thunk).

https://github.com/llvm/llvm-project/pull/138750