RFR 8208648: ECC Field Arithmetic Enhancements

[Adam Petcher]

JBS: https://bugs.openjdk.java.net/browse/JDK-8208648
webrev: http://cr.openjdk.java.net/~apetcher/8208648/webrev.00/

This changeset includes the enhancements to the finite field arithmetic 
library that are necessary for the new implementation of ECDSA and 
ECDH[1]. The actual ECDH and ECDSA changes will be reviewed separately. 
Please see the JBS tickets for more information about the changes, and 
here are some additional notes:

1) This change includes a code generator that produces finite field 
implementations. The generated code is included in the review, and it 
will be checked in to the repository with a comment indicating that it 
is generated and should not be modified directly. Another option is to 
put the code generator into the build process so the generated code does 
not need to be checked in, but it's not clear whether this is a better 
option.
2) Reviewing every line of the generated code is probably not necessary, 
and it is probably better to focus on the code generator itself 
(Fieldgen.jsh). Of course, it is probably a good idea to review the 
generated code for its structure and for opportunities for improvement.



[1] https://bugs.openjdk.java.net/browse/JDK-8208698