[clang] [llvm] [Clang] Add env var for nvptx-arch/amdgpu-arch timeout (PR #102521)

[Joel E. Denny via llvm-commits]

jdenny-ornl wrote:

> Possibly worth increasing it to a minute then,

Should we also land the env var?  If so, I'll just extend this patch.

Either way, any objection to moving `[Default]SecondsToWait`  into executeToolChainProgram so we're maintaining it in just one place?

> this is basically just a last ditch effort to prevent builds from hanging forever. I've had it happen personally where either the CUDA or AMDGPU drivers were stuck, and when I tried to rebuild `libc` `ninja` just hung indefinitely and it took me awhile to figure out why.

I'm not sure how often the situation you describe occurs in practice.  Hopefully a 60-second pause on a simple compilation doesn't prompt the same confusion and a premature Ctrl+C.

https://github.com/llvm/llvm-project/pull/102521