[llvm] [BOLT] Add GNUPropertyRewriter and warn on AArch64 BTI note (PR #161206)

[Gergely Bálint via llvm-commits]

bgergely0 wrote:

Note to reviewers: the newly added GNUPropertyRewriter and the BuildIDRewriter both decode the contents of a note section, so a part of the code is common. 

I can add a follow-up NFC(I) patch later, to merge the two into a new NoteSectionRewriter, that can decode both. 

Should I do that? 

https://github.com/llvm/llvm-project/pull/161206