[clang] [NVPTX] Fix ctor / dtor lowering when NVPTX target is not enabled (PR #124116)

[Jan Patrick Lehr via cfe-commits]

https://github.com/jplehr approved this pull request.

Fixes a build issue I was hitting in https://github.com/llvm/llvm-project/pull/123673

https://github.com/llvm/llvm-project/pull/124116