[clang] [SFrame][Retry] Add assembler option --gsframe (PR #165806)

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Sterling-Augustine wrote:

I'm not sure. This is how the `--allow-experimental-crel` does it, and it doesn't have a check like this. Looking at the commits, I don't think they considered it. Don't know if that is an oversight or intentional. 

I'm personally not inclined to add the second check. But will do so if you think it is worth it.

https://github.com/llvm/llvm-project/pull/165806