xmlsecurity: fix DrMemory warning

Presumably that was the intent?

Change-Id: Ibfca90041d6913827d2f329bab448afe4d725b46
(cherry picked from commit a933990a)

xmlsecurity/source/xmlsec/saxhelper.cxx

@@ -137,7 +137,7 @@ SAXHelper::SAXHelper( )
     {
         xmlSAXVersion(m_pParserCtxt->sax, 1);
 
-        if( m_pParserCtxt->inputTab[0] != nullptr )
+        if (m_pParserCtxt->inputTab != nullptr)
         {
             m_pParserCtxt->inputTab[0] = nullptr ;
         }