ClangCodeModel: Try harder to find out whether a function is virtual

... when following symbols with clangd.
The textdocument/implementation request is expensive, so we'd like to
make sure we only run it if we are sure that we're really dealing with a
virtual function. We re-use the information gathered during highlighting
for this purpose.

Change-Id: Id92a9a92fe2ac7fd5acf903a9ade711223ee401b
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.h

@@ -35,6 +35,7 @@
 
 namespace Core { class SearchResultItem; }
 namespace CppEditor { class CppEditorWidget; }
+namespace LanguageServerProtocol { class Range; }
 namespace ProjectExplorer { class Project; }
 namespace TextEditor { class BaseTextEditor; }
 
@@ -76,6 +77,9 @@ public:
             const LanguageServerProtocol::HoverRequest::Response &hoverResponse,
             const LanguageServerProtocol::DocumentUri &uri);
 
+    void setVirtualRanges(const Utils::FilePath &filePath,
+                          const QList<LanguageServerProtocol::Range> &ranges, int revision);
+
     void enableTesting();
     bool testingEnabled() const;