[clang-tools-extra] clangd: Make callHierarchy follow inheritance (PR #163024)

[Nathan Ridge via cfe-commits]

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@@ -164,6 +164,17 @@ class IndexClient : public clangd::SymbolIndex {
               });
   }
 
+  void reverseRelations(
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HighCommander4 wrote:

`Server.cpp` also needs to be modified to provide an overridden implementations of `ReverseRelations()` on the server side (see impl. of [`Relations()`](https://searchfox.org/llvm/rev/0792478e4e133be96650444f3264e89d002fc058/clang-tools-extra/clangd/index/remote/server/Server.cpp#308) for reference).

https://github.com/llvm/llvm-project/pull/163024