Missing "classpath exception" in LambdaProxyClassArchive.java

JDK-8198698 added:

 src/java.base/share/classes/java/lang/invoke/LambdaProxyClassArchive.java

but it should have the "classpath exception" in its GPL header..

Reported here:

http://mail.openjdk.java.net/pipermail/jdk-dev/2020-July/004557.html

(the other reported files are part of the build system or tests and do not require the CPE)