[lld] [LLD] Merge .hexagon.attributes sections (PR #148098)

[Brian Cain via llvm-commits]

androm3da wrote:

> Can you update the description with the purpose and mention that this is similar to .riscv.attributes (primary patch: https://reviews.llvm.org/D138550)?

Done

> Does Hexagon have a processor supplementary ABI document? Ideally this should be mentioned.

It does: https://docs.qualcomm.com/bundle/publicresource/80-N2040-23_REV_K_Qualcomm_Hexagon_Application_Binary_Interface_User_Guide.pdf

Unfortunately, it's not mentioned in this document.  We should revise this to add the `.hexagon.attributes` there, I agree.  WDYT @quic-akaryaki?

https://github.com/llvm/llvm-project/pull/148098