RFR: JDK-8200083: Bump bootjdk requirement for JDK 11 to JDK 10

[Erik Joelsson]

Now that JDK 10 has been officially released we can update the boot jdk 
requirement for JDK 11. Cross posting this to jdk-dev to raise awareness 
of this rather disruptive change.

This patch changes the requirement on boot jdk version in configure (and 
updates the configuration that controls what JDK to use as boot in 
Oracle's internal build system).

Webrev: http://cr.openjdk.java.net/~erikj/8200083/webrev.01/

Bug: https://bugs.openjdk.java.net/browse/JDK-8200083

/Erik