Clang float 128 bug now in GitHub llvm issue 46903 with first solution

[stefano2734]

Clang float128 bug in readme for hip sycl and cuda:

In Gitlab
https://bugs.llvm.org/show_bug.cgi?id=47559

In GitHub
llvm/llvm-project#46903

With a work around to clang 19.1, but issue 46903 not closed

llvm/llvm-project@318bff6

Actual is clang 20.1.8 and a new test about this bug is possible.