[compiler-rt] [builtins] Fix floattitf.c etc. compilation on Solaris/SPARC (PR #70058)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson approved this pull request.

LGTM, alternatively could also add an explicit check for INT128 availability to this `#if` rather than relying on CRT_HAS_TF_MODE only being defined when int128 also exists.

https://github.com/llvm/llvm-project/pull/70058