[clang] [flang] [flang] Add -f[no-]unroll-loops flag (PR #122906)

[David Truby via cfe-commits]

DavidTruby wrote:

I guess the tests in this should have had --target= for the targets I checked them on (x86_64 and aarch64). I can add those and remove the xfail?

https://github.com/llvm/llvm-project/pull/122906