[Driver][SYCL] Support 64bit long double for SYCL GPU compilation

[jchlanda]

Make sure that -mlong-double-64 option is supported on HIP/Cuda.

[jchlanda]

Fixes: #15852

[jchlanda]

Looks like linux gen12 is experiencing some problems.

[mdtoguchi]

For all of these, I believe the expected option syntax is to use --target=x86_64-unknown-linux-gnu -fsycl-targets=nvptx64-nvidia-cuda. Use of --target=<triple> is preferred over -target <triple> moving forward.

[jchlanda]

Done. I've only updated tests that I've added in this patch.

As a side note, it seems strange that sycl target triple option gets only one hyphen, both seem to be following the same pattern of:

hyphen[hyphen]target_name=triple

but end up spelled out differently:

--target=<triple>

vs:

-fsycl-targets=<triple>

[mdtoguchi]

Use of --target=<triple> is a general option. There are some similar options for offloading that use the double hyphen syntax which are also general in nature for offloading. Consider -fsycl-targets=<target> to be in a similar usage family as -fopenmp-targets=<target>. Moving forward when looking at the new offloading model approach, use of --offload-arch=<arch> would be used to target other devices which better fits within the double hyphen syntax.

[mdtoguchi]

Thanks, LGTM

[jchlanda]

@intel/llvm-gatekeepers this should be ready to roll.

Thank you.

[sommerlukas]

The post-commit failure is unrelated to changes in this PR, the failure is already tracked in #8803.