RFR: 8198571: [JVMCI] must not install wide vector code unless runtime supports it

[Doug Simon]

As shown in https://github.com/oracle/graal/issues/303, a bug in a JVMCI compiler can result in vector code being installed even if the runtime doesn't support it. JVMCI should be defensive and raise an exception in this case.

https://bugs.openjdk.java.net/browse/JDK-8198571
http://cr.openjdk.java.net/~dnsimon/8198571/

-Doug