[vectorIntrinsics] RFR: Trust final fields in jdk/incubator/vector package

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/panama/vector/trust_finals/webrev.00/

To reduce the usage of @Stable, I propose to treat instance final fields 
in jdk/incubator/vector package as trusted by the JVM.

It also requires jdk.incubator.vector module to be lifted from platform 
to boot module.

Best regards,
Vladimir Ivanov