RFR 8056900: Enhance NoClassDefFound exception messaging

[harold seigel]

Hi,

Please review this small JDK-10 change to enhance NoClassDefFoundError 
exception messages.

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8056900/webrev/index.html

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8056900

The change was tested with JCK tests, the JTreg hotspot, java/io, 
java/lang, java/util and other tests, the RBT tier2 -tier5 tests, the 
co-located NSK tests, JPRT, and with the new test provided with the change.

Thanks, Harold