[clang] [CUDA][HIP] add option -gpuinc (PR #140106)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

> > > > > Hmm, in what cases is `-nogpuinc` added when we don't actually want it? I think we should avoid adding `-nogpuinc` if it's not needed, if possible.
> > > > 
> > > > 
> > > > comgr is the JIT compiler for HIP on ROCm. comgr uses -nogpuinc by default. However, some users of comgr need to override that so that comgr enables the wrapper headers. We cannot simply let comgr stop using -nogpuinc by default since it will break existing comgr users. Then we need to add -gpuinc to override that.
> > > 
> > > 
> > > I guess it's too bothersome to manually add `-include`?
> > 
> > 
> > The user app of comgr does not know about the clang wrapper path and name, which is internals of clang and may change.
> 
> Is it really easier to patch clang over comgr?

It is possible to patch comgr, but I think in general we better to have pairs of flag to be able to override them. The same request popped up before for some reasons.

https://github.com/llvm/llvm-project/pull/140106