Internals: More const. No functional change intended.

src/V3Assert.cpp

@@ -30,7 +30,7 @@ private:
     // NODE STATE/TYPES
     // Cleared on netlist
     //  AstNode::user()         -> bool.  True if processed
-    AstUser1InUse m_inuser1;
+    const AstUser1InUse m_inuser1;
 
     // STATE
     AstNodeModule* m_modp = nullptr;  // Last module