related tdf#47471 textgraphic: use stylename if autostyle missing

The same fix for 47471 should also be useful for textgraphics.

Change-Id: I27cef6bd22fbc4f2a94fb17231a3c385987364e0
Reviewed-on: https://gerrit.libreoffice.org/65619
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>

xmloff/source/text/txtparae.cxx

@@ -3076,8 +3076,9 @@ void XMLTextParagraphExport::_exportTextGraphic(
         rPropSet->getPropertyValue( gsFrameStyleName ) >>= sStyle;
     }
 
-    OUString sAutoStyle( sStyle );
-    sAutoStyle = Find( XML_STYLE_FAMILY_TEXT_FRAME, rPropSet, sStyle );
+    OUString sAutoStyle = Find( XML_STYLE_FAMILY_TEXT_FRAME, rPropSet, sStyle );
+    if ( sAutoStyle.isEmpty() )
+        sAutoStyle = sStyle;
     if( !sAutoStyle.isEmpty() )
         GetExport().AddAttribute( XML_NAMESPACE_DRAW, XML_STYLE_NAME,
                                   GetExport().EncodeStyleName( sAutoStyle ) );