[llvm] [llvm-strings] Add --encoding={s,S,utf8} option (PR #221794)

[via llvm-commits]

https://github.com/aokblast commented:

I am wondering if it will cause performance regression. Since the read function is much larger than before and default jumps to Encoding::Locale.

https://github.com/llvm/llvm-project/pull/221794