[compiler-rt] [builtins] Guard the divtc3_test.c test with CRT_HAS_TF_MODE (PR #71876)

[Alexander Richardson via llvm-commits]

arichardson wrote:

> I think it's something to do with the clang version on the bot being older by a few years. I'm not entirely sure, can this go in anyway since we need to get it back to green?

I'm happy for this to be merged, but could you file an issue that the feature detection is broken?

https://github.com/llvm/llvm-project/pull/71876