[clang] [Clang] Added nullptr check to getFriendDecl access (PR #121056)

[Matheus Izvekov via cfe-commits]

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@@ -886,6 +886,7 @@ Bug Fixes to C++ Support
   out of a module (which is the case e.g. in MSVC's implementation of ``std`` module). (#GH118218)
 - Fixed a pack expansion issue in checking unexpanded parameter sizes. (#GH17042)
 - Fixed a bug where captured structured bindings were modifiable inside non-mutable lambda (#GH95081)
+- Fixed a crash when parsing a friend declaration and a defaulted operator.
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mizvekov wrote:

```suggestion
- Fixed a crash when parsing a friend declaration and a defaulted operator (#GH120857).
```

https://github.com/llvm/llvm-project/pull/121056