[clang] [clang][AST] Add 'IgnoreTemplateParmDepth' to structural equivalence cache (PR #115518)

[Donát Nagy via cfe-commits]

================
@@ -1804,8 +1804,10 @@ struct StructuralEquivalenceCacheTest : public StructuralEquivalenceTest {
   }
 
   template <typename NodeType>
-  bool isInNonEqCache(std::pair<NodeType *, NodeType *> D) {
-    return NonEquivalentDecls.count(D) > 0;
+  bool isInNonEqCache(std::pair<NodeType *, NodeType *> D,
+                      bool IgnoreTemplateParmDepth = false) {
+    return NonEquivalentDecls.count(
+               std::make_tuple(D.first, D.second, IgnoreTemplateParmDepth)) > 0;
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NagyDonat wrote:

```suggestion
    return NonEquivalentDecls[IgnoreTemplateParmDepth].count(D) > 0;
```

https://github.com/llvm/llvm-project/pull/115518