[clang] [flang] [compiler-rt] [libc] [clang-tools-extra] [libcxx] [llvm] [clang][FatLTO] Avoid UnifiedLTO until it can support WPD/CFI (PR #79061)

[Paul Kirth via cfe-commits]

ilovepi wrote:

Since this has passed Linux premerge checks and I think Windows CI is having some issues I tested this locally on a Windows machine and its passing. I'm going to go ahead and merge.

https://github.com/llvm/llvm-project/pull/79061