[clang] [Draft][HIP][Driver] Use alternative `/lib64` if `/lib` doesn't exist (PR #211587)

[Juan Manuel Martinez Caamaño via cfe-commits]

jmmartinez wrote:

> > > if /lib does not exists and /lib64 does, use the later.
> > > If both exist /lib is preferred.
> > 
> > 
> > @jmmartinez the `.../lib` dir exists as well. However, most of the libraries end up in `.../lib64`.
> 
> Why does this happen exactly? We control the toolchain so we should state the rules for where and why libraries show up. Having a 64 suffix is common, it happens in some LLVM distributions, so we should determine a priority order if we support it.

It seems that some libraries (something from the profiler) ended up in `lib/` since the path was hardcoded. But otherwise the runtime libraries all ended up in `lib64/`.

In the last commit I've updated the patch to use the path where the amdhip64 library resides.

https://github.com/llvm/llvm-project/pull/211587