[clang] [clang][bytecode] Implement constexpr step limit (PR #176150)

[Timm Baeder via cfe-commits]

================
@@ -184,6 +188,7 @@ class InterpState final : public State, public SourceMapper {
   SmallVectorImpl<PartialDiagnosticAt> *PrevDiags = nullptr;
   unsigned SpeculationDepth = 0;
   std::optional<bool> ConstantContextOverride;
+  unsigned StepsLeft;
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tbaederr wrote:

We have this in `ExprConstant.cpp`:
```c++
    bool nextStep(const Stmt *S) {
      if (Ctx.getLangOpts().ConstexprStepLimit == 0)
        return true;
```
so... `0` means infinite steps? Which this patch doesn't properly implement and can't be tested I guess.

https://github.com/llvm/llvm-project/pull/176150