[llvm] [Offload] Store kernel name in GenericKernelTy (PR #142799)

[Ross Brunton via llvm-commits]

RossBrunton wrote:

As well as the various `INFO` calls, it is also used for the Record/Replay thing. Regardless, I think the following is UB with current liboffload:

```c++
ol_kernel_handle_t kernel;
if (someOption()) {
  std::string name = getOptionValue();
  olGetKernel(program, name.c_str(), &kernel);
} else {
  olGetKernel(program, "main", &kernel);
}
olLaunchKernel(device, kernel, [...]);
```

Although I think it might only be UB when certain debugging flags are set (which probably is going to make it more of a pain if there are issues).

https://github.com/llvm/llvm-project/pull/142799