Change recursive to loop in allIncludesForDocument

Change-Id: I110294efa506b5a038cfc7f4202fab001e3eefd3
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/cplusplus/CppDocument.h

@@ -450,8 +450,6 @@ public:
     bool operator==(const Snapshot &other) const;
 
 private:
-    void allIncludesForDocument_helper(const QString &fileName, QSet<QString> &result) const;
-
     mutable DependencyTable m_deps;
     Base _documents;
 };