Internals: Make AstConstraintBefore an AstNodeStmt (#6280) (#8141)

AstConstraintBefore ('solve x before y') is a constraint item that appears
in constraint bodies alongside its siblings AstConstraintExpr,
AstConstraintUnique and AstConstraintIf, all of which are AstNodeStmt.
Part of #6280.

src/V3AstNodeOther.h

@@ -1041,22 +1041,6 @@ public:
     void isStatic(bool flag) { m_isStatic = flag; }
     bool isStatic() const { return m_isStatic; }
 };
-class AstConstraintBefore final : public AstNode {
-    // Constraint solve before item
-    // @astgen op1 := lhssp : List[AstNodeExpr]
-    // @astgen op2 := rhssp : List[AstNodeExpr]
-public:
-    AstConstraintBefore(FileLine* fl, AstNodeExpr* lhssp, AstNodeExpr* rhssp)
-        : ASTGEN_SUPER_ConstraintBefore(fl) {
-        addLhssp(lhssp);
-        addRhssp(rhssp);
-    }
-    ASTGEN_MEMBERS_AstConstraintBefore;
-    bool isGateOptimizable() const override { return false; }
-    bool isPredictOptimizable() const override { return false; }
-    bool sameNode(const AstNode* /*samep*/) const override { return true; }
-};
-
 class AstCoverBin final : public AstNode {
     // Captures data for a coverpoint 'bins' declaration
     // @astgen op1 := rangesp : List[AstNode]

src/V3AstNodeStmt.h

@@ -461,6 +461,21 @@ public:
     bool sameNode(const AstNode* samep) const override { return true; }  // Ignore name in comments
     virtual bool showAt() const { return m_showAt; }
 };
+class AstConstraintBefore final : public AstNodeStmt {
+    // Constraint solve before item
+    // @astgen op1 := lhssp : List[AstNodeExpr]
+    // @astgen op2 := rhssp : List[AstNodeExpr]
+public:
+    AstConstraintBefore(FileLine* fl, AstNodeExpr* lhssp, AstNodeExpr* rhssp)
+        : ASTGEN_SUPER_ConstraintBefore(fl) {
+        addLhssp(lhssp);
+        addRhssp(rhssp);
+    }
+    ASTGEN_MEMBERS_AstConstraintBefore;
+    bool isGateOptimizable() const override { return false; }
+    bool isPredictOptimizable() const override { return false; }
+    bool sameNode(const AstNode* /*samep*/) const override { return true; }
+};
 class AstConstraintExpr final : public AstNodeStmt {
     // Constraint expression
     // @astgen op1 := exprp : AstNodeExpr