RFR: JDK-8236266: change error message for the case when a class extends j.l.Record

[Vicente Romero]

Please review this one liner fix to [1] at [2]. This is just a minor 
change in an error message.Currently if a class extends class: 
j.l.Record, javac shows the following error message:

ExtendingRecordClass.java:1: error: records cannot directly extend Record
class Test extends Record {}
^

when Test is not a record but a class. This fix updates the error message,

Thanks,
Vicente

[1] https://bugs.openjdk.java.net/browse/JDK-8236266
[2] http://cr.openjdk.java.net/~vromero/8236266/webrev.00/