[llvm] [llvm] Win x64 Unwind V2 1/n: Mark beginning and end of epilogs (PR #110024)

[Daniel Paoliello via llvm-commits]

dpaoliello wrote:

> Overall, this seems fine, but I'd like to see some description of the binary layout before we start landing patches.

@efriedma-quic did you want the full documentation on learn.microsoft.com, or would updating readobj/objdump to handle the new unwind codes be sufficient?

https://github.com/llvm/llvm-project/pull/110024