[llvm] RuntimeLibcalls: Stop opting out of exp10 (PR #148604)

[Trevor Gross via llvm-commits]

tgross35 wrote:

For my understanding: this is expected to ICE because there is no possible libcall here (since `exp10l` is `f64` on Apple) and not because ICEs are expected when the default target lib isn't known to provide a symbol, right? Otherwise I would be a bit concerned about our ability to make `fp128` work cross-platform by vendoring needed symbols (unrelated to this change of course). 

https://github.com/llvm/llvm-project/pull/148604