[clang] [flang] [llvm] add -floop-fuse to clang and flang (PR #142686)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj commented:

FWIW, using merge instead of rebase might be a better. That way, you might avoid resolving the same conflicts repeatedly.

https://github.com/llvm/llvm-project/pull/142686