[llvm] Use thinlto and pgo for x86_64 windows release packaging (PR #71067)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

A quick side question regarding PGO (while listening in on this topic); how portable is the profile information across builds? If I e.g. build Clang on Linux, then do some profiling with that, I can use that to do a new Clang build for Linux with PGO. But can I use the same profile information for PGO when I, still on Linux, cross compile Clang to run on Windows?

https://github.com/llvm/llvm-project/pull/71067