Internals: More const. No functional change intended.

src/V3Clean.cpp

@@ -42,9 +42,9 @@ private:
     //  AstNode::user()         -> CleanState.  For this node, 0==UNKNOWN
     //  AstNode::user2()        -> bool.  True indicates widthMin has been propagated
     //  AstNodeDType::user3()   -> AstNodeDType*.  Alternative node with C size
-    AstUser1InUse m_inuser1;
-    AstUser2InUse m_inuser2;
-    AstUser3InUse m_inuser3;
+    const AstUser1InUse m_inuser1;
+    const AstUser2InUse m_inuser2;
+    const AstUser3InUse m_inuser3;
 
     // TYPES
     enum CleanState : uint8_t { CS_UNKNOWN, CS_CLEAN, CS_DIRTY };