[compiler-rt] [compiler-rt] [test] Fix using toolchains that rely on Clang default configs (PR #113491)

[Vitaly Buka via llvm-commits]

vitalybuka wrote:

it breaks several bots like this https://lab.llvm.org/buildbot/#/builders/164/builds/3908

https://github.com/llvm/llvm-project/pull/113491