[clang-tools-extra] [clangd] Add config option to allow detection of unused system headers (PR #87208)

[kadir çetinkaya via cfe-commits]

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@@ -254,6 +254,10 @@ struct Fragment {
       /// unused or missing. These can match any suffix of the header file in
       /// question.
       std::vector<Located<std::string>> IgnoreHeader;
+
+      /// If false (default), unused system headers will be ignored.
+      /// Standard library headers are analyzed regardless of this option.
+      std::optional<Located<bool>> AnalyzeSystemHeaders;
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kadircet wrote:

Same renaming suggestion here for `s/SystemHeaders/AngledIncludes`

https://github.com/llvm/llvm-project/pull/87208