RFR: Value types consistency checks

[Frederic Parain]

Please review this changeset implementing consistency checks based on the
ValueTypes attribute. These checks ensure that the assumptions a class has
about value types, as encoded in its ValueTypes attribute, match the
reality, or the assumptions of another class it links to.

The details of the consistency checks have been summarized by Karen in
this document:
http://cr.openjdk.java.net/~acorn/value-types-consistency-checking-details.pdf

If the implementation doesn’t match the document, this is likely to be bug,
so please, report it.

Some tests using the Bytecodes API have been updated to include a
ValueTypes attribute in the class files they generate (thanks to Srikanth
for adding this feature to the Bytecodes API).

Webrev:
http://cr.openjdk.java.net/~fparain/VTAttributeChecks/webrev.01/

Thank you,

Fred