Map from GetLastError() to HRESULT

clang-cl reported "error: comparison of integers of different signs: 'DWORD'
(aka 'unsigned long') and 'HRESULT' (aka 'long') [-Werror,-Wsign-compare]"

Change-Id: I568f03bd863ba63e30143483d9573042f3506de7
Reviewed-on: https://gerrit.libreoffice.org/42597Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Jenkins <ci@libreoffice.org>

xmlsecurity/qa/unit/pdfsigning/pdfsigning.cxx

@@ -190,7 +190,7 @@ bool PDFSigningTest::sign(const OUString& rInURL, const OUString& rOutURL, size_
                 if (!bSignResult)
                 {
                     DWORD dwErr = GetLastError();
-                    if (dwErr == CRYPT_E_NO_KEY_PROPERTY)
+                    if (HRESULT_FROM_WIN32(dwErr) == CRYPT_E_NO_KEY_PROPERTY)
                     {
                         SAL_WARN("xmlsecurity.pdfio.test", "Skipping a certificate without a private key");
                         continue; // The certificate does not have a private key - not a valid certificate