RFR JDK-8207815: [lworld] JVM_GetArrayElement and, JVM_SetArrayElement don't work for flatten array

[mandy chung]

Array::get and Array::set call JVM_GetArrayElement and
JVM_SetArrayElement function to get and set an array element.
The JVM entry points don't support flattened arrays.

Instead of adding the flatten array support in JVM_GetArrayElement
and JVM_SetArrayElement, it's straight-forward to do that in
Array::get and Array::set in Java.

Webrev:
 
http://cr.openjdk.java.net/~mchung/valhalla/webrevs/8207815/webrev.00/index.html

Mandy