RFR: 8129446: crash when reporting corrupted classfile

[Kim Barrett]

Please review this fix to a recent change in the construction of an
error message.  We enlarge the buffer for message construction to fit
known messages, and also now use jio_snprintf to ensure we don't
overrun the enlarged buffer.

CR:
https://bugs.openjdk.java.net/browse/JDK-8129446

Webrev:
http://cr.openjdk.java.net/~kbarrett/8129446/webrev.01/

Testing:
jprt, local jtreg