RFR 9: 8139390 : Very long classname in jimage causes SIGSEGV

[Roger Riggs]

Please review an update to the jimage reader implementation to correct the
case where a class name is very long causing a SEGV due to buffer overruns.

The fix will be pushed to the hs-comp repo; the bug was first spotted there.

Webrev:
    http://cr.openjdk.java.net/~rriggs//webrev-jimage-segv-8139390

Issue:
    https://bugs.openjdk.java.net/browse/JDK-8139390

Thanks, Roger