[9] RFR 8028727: warnings from b116 for jdk.src.share.native.sun.security.ec: JNI pending exceptions

[Vincent Ryan]

Please review this patch for better handling of JNI pending exceptions 
in the ECC native code:

Webrev:  http://cr.openjdk.java.net/~vinnie/8028727/webrev.00/

The patch examines the return code from JNI calls to check whether an
exception is already pending. If so then it cleans up and returns.

Thanks.