RFR: 8163373: Rewrite GenerateJLIClassesPlugin to avoid reflective calls into java.lang.invoke

[Claes Redestad]

Hi,

please review this patch to replace reflection calls into 
java.lang.invoke from GenerateJLIClassesPlugin with an internal API 
exported to jdk.jlink via JavaLangInvokeAccess/SharedSecrets.

Webrev: http://cr.openjdk.java.net/~redestad/8163373/webrev.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8163373

Thanks!

/Claes