[compiler-rt] [compiler-rt][test] Add REQUIRES: shell to focus-function.test with for-loop (PR #106150)

[Florian Mayer via llvm-commits]

fmayer wrote:

general nit about this CL: i think it wouldn't hurt to add a comment next to the `REQUIRES: shell` saying why

https://github.com/llvm/llvm-project/pull/106150