fastparser: avoid boost::optional where it is un-necessary.

boost::optional appears to show up rather heavily on many profiles.
We already use mnElementToken == DONTKNOW to flag / use these guys.

Change-Id: Ibf2b0167f259cc601da2fb9703e880b78e60886e
diff --git a/sax/source/fastparser/fastparser.cxx b/sax/source/fastparser/fastparser.cxx
index 8f02e4f..8c8ab1b 100644
--- a/sax/source/fastparser/fastparser.cxx
+++ b/sax/source/fastparser/fastparser.cxx
@@ -96,10 +96,10 @@ struct NameWithToken

struct SaxContext
{
    ::com::sun::star::uno::Reference< ::com::sun::star::xml::sax::XFastContextHandler > mxContext;
    sal_Int32                   mnElementToken;
    boost::optional< OUString > maNamespace;
    boost::optional< OUString > maElementName;
    Reference< XFastContextHandler > mxContext;
    sal_Int32 mnElementToken;
    OUString  maNamespace;
    OUString  maElementName;

    SaxContext( sal_Int32 nElementToken, const OUString& aNamespace, const OUString& aElementName ):
            mnElementToken(nElementToken)
@@ -488,7 +488,7 @@ void Entity::endElement()
        if( nElementToken != FastToken::DONTKNOW )
            xContext->endFastElement( nElementToken );
        else
            xContext->endUnknownElement( aContext.maNamespace.get(), aContext.maElementName.get() );
            xContext->endUnknownElement( aContext.maNamespace, aContext.maElementName );
    }
    catch (const Exception& e)
    {