[CUDA] Compilation for NVPTX target doesn't support -fsycl-device-code-split

[bader]

Only off value for -fsycl-device-code-split is compatible with -fsycl-targets= set for NVIDIA CUDA API.

Should we add support for -fsycl-device-code-split?

Revealed by KhronosGroup/SYCL-CTS#51.

[bader]

@Naghasan, FYI.

[AidanBeltonS]

NVPTX64 support for module splitting has been added with #4107
llvm-test-suite has DeviceCodeSplit/split-per-kernel.cpp passing but failing with DeviceCodeSplit/split-per-source-main.cpp failing.

Investigation showed that failure was due to the CUDA plugin being unable to find the kernel names in the binary.
This is because the current implementation uses a regex search, which cannot create a list of names for piProgramGetInfo with module splitting per source.

Proposed fix: #4565
Add piProgramHasKernel to PI and use cuModuleGetFunction and avoid creating a list of function names owned by a program with a regex search.

A secondary pull request to llvm-test-suite will be made once #4565 passes to enable DeviceCodeSplit/split-per-kernel.cpp and DeviceCodeSplit/split-per-source-main.cpp for CUDA and HIP backends.

[AerialMantis]

We believe this issue to be resolved by merging #4599, so we're closing the ticket.