[llvm] [BOLT][AArch64] Relax calls and branches with fragment clusters (PR #215825)

[Adam Bzowski via llvm-commits]

adam-bzowski-arm wrote:

This appears to address one of the main problems described in #218885: calls from main and cold fragments were previously grouped by whole function and could be redirected to a thunk in the wrong section.

The issue also contains reproducers involving function padding, boundary markers, skipped functions, hugify placement and alignment. It may be useful to test this patch against those cases as well.

https://github.com/llvm/llvm-project/pull/215825