RFR: JDK-8242863: Bump minimum boot jdk to JDK 14

[Joe Darcy]

Looks fine Erik; thanks,

-Joe

On 4/16/2020 9:54 AM, Erik Joelsson wrote:
> JDK 14 is now GA. The minimum boot JDK version for mainline/JDK 15 
> should be bumped to this version.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8242863
>
> Webrev: http://cr.openjdk.java.net/~erikj/8242863/webrev.01/index.html
>
> /Erik
>