[clang] [clang][PowerPC] Enable IEEE-128 long double on FreeBSD/powerpc64le (PR #201298)

[Jessica Clarke via cfe-commits]

jrtc27 wrote:

What's the story with the runtimes? Since I left feedback here I came across the following comment of yours in the FreeBSD review (https://reviews.freebsd.org/D57388#1314874):

> compiler-rt part can't be upstreamed, because this is a hack -
> compiler-rt does not support kf type ldbl functions that powerpc64le
> needs. Upstream usually just uses libgcc (from GCC) for that.

We can't just go changing ABI if it's going to break runtimes, and any requisite support needs to go upstream first.

https://github.com/llvm/llvm-project/pull/201298