RFR (XS) JDK-8185673: assertion failure when creating an array of empty value type

[David Simms]

Hello,

Bug: https://bugs.openjdk.java.net/browse/JDK-8185673

Webrev: http://cr.openjdk.java.net/~dsimms/valhalla/8185673/

We have multiple issues supporting empty value types at this point in 
time. For minimal value types, we will live with this as a system 
limitation and throw a ClassFormatError, rather than assert or crash.

Testing: New jtreg "Empty" passes for both fastdebug and release builds.

Cheers
/David Simms