Improve error display of decode test failures.
Improve error display of decode test failures.

nullstyle/go-xdr,dajohi/go-xdr,rasky/go-xdr,davecgh/go-xdr,rasky/go-xdr,dajohi/go-xdr,postfix/go-xdr,postfix/go-xdr,davecgh/go-xdr,nullstyle/go-xdr