[clang] [AMDGPU] Do not enable GPU sanitizers by default (PR #126090)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> This may break ROCm santizer builds since whether santizer is on should be determined by -fsanitize only, i.e. by default -fgpu-sanitize should be on.

Yeah @ampandey-1995 will fix it properly, the issue with the previous patch was that it was enabling it for *all* compilations because it considered `-fgpu-sanitize` always on regardless of `-fsanitize`.

https://github.com/llvm/llvm-project/pull/126090