Fix unused variable compile error (#6222 partial)

src/V3LinkCells.cpp

@@ -112,7 +112,6 @@ class LinkCellsVisitor final : public VNVisitor {
     VSymGraph m_mods;  // Symbol table of all module names
     LinkCellsGraph m_graph;  // Linked graph of all cell interconnects
     LibraryVertex* m_libVertexp = nullptr;  // Vertex at root of all libraries
-    int m_dedupNum = 0;  // Package dedup number
     const V3GraphVertex* m_topVertexp = nullptr;  // Vertex of top module
     std::unordered_set<string> m_declfnWarned;  // Files we issued DECLFILENAME on
     string m_origTopModuleName;  // original name of the top module