enable truncation for DSA digests prior to signing

This works around a bug in OpenSSL 1.0.0, 1.0.0a, and 1.0.0b where SHA-2
is a supported signature algorithm but FIPS 186-3 truncation is not
performed if the q value is smaller than the digest output length
add the missing file. i are senior dvlpr
update comment with info re: 0.9.8
Merge pull request #1384 from reaperhulk/fix-1382

enable truncation for DSA digests prior to signing