xmlsecurity mscrypto PDF sign: conditionally add back CAdES SubFilter

We can now write that on Windows as well when requested, after the
signing-certificate attribute is implemented using mscrypto.

With this, the PAdES validator at
<http://signatures-conformance-checker.etsi.org/protected/upload.php?sigtype=padesconf>
finds our Windows signature valid.

Change-Id: Iaeb4c36a1eac14e3d3c3c12d9cfd9529e7663f77
Reviewed-on: https://gerrit.libreoffice.org/31162
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>
diff --git a/xmlsecurity/source/pdfio/pdfdocument.cxx b/xmlsecurity/source/pdfio/pdfdocument.cxx
index 648cc4b..1537500 100644
--- a/xmlsecurity/source/pdfio/pdfdocument.cxx
+++ b/xmlsecurity/source/pdfio/pdfdocument.cxx
@@ -375,13 +375,9 @@ sal_Int32 PDFDocument::WriteSignatureObject(const OUString& rDescription, bool b
    comphelper::string::padToLength(aContentFiller, MAX_SIGNATURE_CONTENT_LENGTH, '0');
    aSigBuffer.append(aContentFiller.makeStringAndClear());
    aSigBuffer.append(">\n/Type/Sig/SubFilter");
#ifdef XMLSEC_CRYPTO_NSS
    if (bAdES)
        aSigBuffer.append("/ETSI.CAdES.detached");
    else
#else
    (void)bAdES;
#endif
        aSigBuffer.append("/adbe.pkcs7.detached");

    // Time of signing.