xmlsecurity: fix the PDF incremental update's cross-references table

The VCL pdf export writes a space after the in-use entry, and turns out
Adobe Acrobat starts to "repair" the file if there is no such space.
Which means the signature is validated against the repaired document,
resulting in a "The signature byte range is invalid" error message,
hiding the root cause.

Not that ISO-32000 7.5.4 "Cross-References Table" would mention the need
for such whitespace at the end of the lines.

Change-Id: I165b57809550f184f374c00f28426a3cd813c63f

xmlsecurity/source/pdfio/pdfdocument.cxx

@@ -462,9 +462,9 @@ bool PDFDocument::Sign(const uno::Reference<security::XCertificate>& xCertificat
         while (aBuffer.getLength() < 10)
             aBuffer.insert(0, "0");
         if (nObject == 0)
-            aBuffer.append(" 65535 f\n");
+            aBuffer.append(" 65535 f \n");
         else
-            aBuffer.append(" 00000 n\n");
+            aBuffer.append(" 00000 n \n");
         m_aEditBuffer.WriteOString(aBuffer.toString());
     }