Coverity static analysis, suspicious bitwise logical expression, DigestUtil (Elytron)

Coverity found suspicious logical operation https://scan7.coverity.com/reports.htm#v23632/p11778/fileInstanceId=9563899&defectInstanceId=2359232&mergedDefectId=1377462

See detailed description of possible problem in [1]

If I extend DigestUtilTest#testDecodeByteOrderedInteger with case from [1], test fails

        byte[] inputFF = CodePointIterator.ofString("000000FF").hexDecode().drain();
        assertEquals(0xFF, decodeByteOrderedInteger(inputFF, 0, 4));

If I change decodeByteOrderedInteger implementation according to [1], all tests passes.

result |= (buf[offset + i] & 0xff);

[1] http://findbugs.sourceforge.net/bugDescriptions.html#BIT_IOR_OF_SIGNED_BYTE

Setting to high priority, because correct behavior of SASL Digest mechanism could be impacted.