[clang] [HIP] Pass `-O0` by default for HIP no-RDC compilations (PR #211790)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Isn't this what you get by not passing no -O flag? I'd rather take the no-opts by default than explicitly using -O0

The linked PR has the background, there's a complaint that moving to LTO regressed the DWARF information

https://github.com/llvm/llvm-project/pull/211790