8314181: [lw5] the check for illegal circularity should only be done if value classes are available

Author: Vicente Romero

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java

@@ -3178,7 +3178,7 @@ public void complete(Symbol sym) throws CompletionFailure {
 
     // A value class cannot contain a non-nullable instance field of its own type either directly or indirectly.
     void checkNonCyclicMembership(ClassSymbol csym) {
-        if (!csym.type.hasImplicitConstructor()) {
+        if (!allowValueClasses || !csym.type.hasImplicitConstructor()) {
             // nothing to see here
             return;
         }