[clang] [Serialization] Read the initializer for interesting static variables before consuming it (PR #92353)

[Kai Nacke via cfe-commits]

redstar wrote:

I can reproduce the failure. The problem is that the CHECK line 

```
// CHECK: [[A_CALL:%[a-zA-Z0-9]+]] = call{{.*}}@_Z6MakeVRffff(
```

assumes that a value is returned. On SystemZ, the return value is passed as `sret` argument, and the function itself returns `void`, so the pattern does not match.

https://github.com/llvm/llvm-project/pull/92353