[compiler-rt] [builtins] Support building the 128-bit float functions on ld80 platforms (PR #68132)

[Alexander Richardson via llvm-commits]

arichardson wrote:

> Aside: x86-64 Android uses a IEEE128 (binary128) long double, and I think it's already using compiler-rt's `__divtc3` / `__divtf3` functions.

Ah that's interesting, was not aware of that. Updated the title to "ld80 platforms" instead.

https://github.com/llvm/llvm-project/pull/68132