[clang] [llvm] [CIR][CUDA] Introduce cu.var_registration for shadow and attach device-side var metadata, internalize device side variables, and lower poison attribute (PR #190087)

[Akimasa Watanuki via cfe-commits]

================
@@ -34,7 +34,7 @@ class CIRGenCUDARuntime {
   CIRGenModule &cgm;
 
 public:
-  CIRGenCUDARuntime(CIRGenModule &cgm) : cgm(cgm) {}
+  CIRGenCUDARuntime(CIRGenModule &cgm);
----------------
Men-cotton wrote:

```suggestion
  CIRGenCUDARuntime(CIRGenModule &cgm) : cgm(cgm) {}
```

I believe the change here can be reverted, and the diffs on clang/lib/CIR/CodeGen/CIRGenCUDARuntime.cpp can be omitted.

https://github.com/llvm/llvm-project/pull/190087