8231262: Suppress warnings on non-serializable instance fields in security libs serializable classes

Reviewed-by: mullan, chegar

src/java.base/share/classes/javax/security/auth/Subject.java

@@ -111,6 +111,7 @@ public final class Subject implements java.io.Serializable {
      *          {@code java.security.Principal}.
      *          The set is a {@code Subject.SecureSet}.
      */
+    @SuppressWarnings("serial") // Not statically typed as Serializable
     Set<Principal> principals;
 
     /**