[HIP] Make `--offload-add-rpath` alias of `-frtlib-add-rpath`

[yaxunl]

Summary

HIP runtime is the language runtime of HIP. When users need
to specify rpath, they usually need to specify rpath for
both compiler-rt and HIP runtime. It seems redundant
to have separate options. Therefore make --offload-add-rpath
an alias to -frtlib-add-rpath.

[tra]

LGTM,

clang/include/clang/Driver/Options.td

4257

I'm not sure these HIP-specific details are needed here.
It may be better to generalize the generic description along the lines of "adds required architecture-specific directories to RPATH".

clang/test/Driver/hip-runtime-libs-linux.hip

16

I think you may still want to test with --offload-add-rpath, too.

[MaskRay]

Seems fine. Should we eventually remove --offload-add-rpath and -fopenmp-implicit-rpath?

[yaxunl]

In D145393#4172429, @MaskRay wrote:

Seems fine. Should we eventually remove --offload-add-rpath and -fopenmp-implicit-rpath?

I agree we should eventually remove them and keep -frtlib-add-rpath only.

clang/include/clang/Driver/Options.td

4257

currently, it only adds compiler-rt path and HIP runtime path to RPATH. Making the help message generic for all language runtime will cause an incorrect impression to the users that this option adds all language runtime lib paths to RPATH but it actually does not.

clang/test/Driver/hip-runtime-libs-linux.hip

16

will do