[clang-tools-extra] [clangd] Re-land "support outgoing calls in call hierarchy" (PR #117673)

[kadir çetinkaya via cfe-commits]

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@@ -108,7 +109,7 @@ class FileSymbols {
 /// FIXME: Expose an interface to remove files that are closed.
 class FileIndex : public MergedIndex {
 public:
-  FileIndex();
+  FileIndex(bool SupportContainedRefs = true);
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kadircet wrote:

same with the default param

https://github.com/llvm/llvm-project/pull/117673