Code review request: 7142888: sun/security/tools/jarsigner/ec.sh fail on sparc

[Vincent Ryan]

Please review the following change:
  http://cr.openjdk.java.net/~vinnie/7142888/webrev.00/

for http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7142888

Some implementations of the SHA512withECDSA signing algorithm require
that the signing/validation key is at least 512 bits.

Thanks.