No need to pass string literals as char* here

The point is creating OUString from ASCII anyway

Change-Id: I9b1e96c41bc13d924bd6194812a7230e2dd6ab78
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/85830
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
diff --git a/oox/source/drawingml/diagram/diagram.cxx b/oox/source/drawingml/diagram/diagram.cxx
index b2f3373..d4e8f18 100644
--- a/oox/source/drawingml/diagram/diagram.cxx
+++ b/oox/source/drawingml/diagram/diagram.cxx
@@ -159,12 +159,12 @@ static uno::Reference<xml::dom::XDocument> loadFragment(

static void importFragment( core::XmlFilterBase& rFilter,
                     const uno::Reference<xml::dom::XDocument>& rXDom,
                     const char* pDocName,
                     const OUString& rDocName,
                     const DiagramPtr& pDiagram,
                     const rtl::Reference< core::FragmentHandler >& rxHandler )
{
    DiagramDomMap& rMainDomMap = pDiagram->getDomMap();
    rMainDomMap[OUString::createFromAscii(pDocName)] = rXDom;
    rMainDomMap[rDocName] = rXDom;

    uno::Reference<xml::sax::XFastSAXSerializable> xSerializer(
        rXDom, uno::UNO_QUERY_THROW);