[clang-tools-extra] [clang-doc] fix flaky test in clang-doc (PR #101387)

[Paul Kirth via cfe-commits]

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@@ -384,5 +384,12 @@ ClangDocContext::ClangDocContext(tooling::ExecutionContext *ECtx,
   }
 }
 
+void ScopeChildren::sort() {
+  std::sort(Namespaces.begin(), Namespaces.end());
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ilovepi wrote:

Prefer llvm::sort. https://llvm.org/docs/CodingStandards.html#beware-of-non-deterministic-sorting-order-of-equal-elements

https://github.com/llvm/llvm-project/pull/101387