Avoid undefined MSO_LineStyle values outside the enum's value range

Change-Id: Ie9eee91374818cbfbb10a7d91e0fb2114ce140b4

filter/source/msfilter/msdffimp.cxx

@@ -5357,7 +5357,7 @@ SdrObject* SvxMSDffManager::ProcessObj(SvStream& rSt,
                             ? (MSO_LineStyle)GetPropertyValue(
                                                 DFF_Prop_lineStyle,
                                                 mso_lineSimple )
-                            : (MSO_LineStyle)USHRT_MAX;
+                            : MSO_LineStyle_NONE;
         pTextImpRec->eLineStyle = pImpRec->eLineStyle;
 
         pImpRec->eLineDashing = (MSO_LineDashing)GetPropertyValue(

include/svx/msdffdef.hxx

@@ -1002,7 +1002,8 @@ enum MSO_LineStyle {
    mso_lineDouble,          // Double lines of equal width
    mso_lineThickThin,       // Double lines, one thick, one thin
    mso_lineThinThick,       // Double lines, reverse order
-   mso_lineTriple           // Three lines, thin, thick, thin
+   mso_lineTriple,          // Three lines, thin, thick, thin
+   MSO_LineStyle_NONE = USHRT_MAX
 };
 
 // MSO_LINETYPE - how to "fill" the line contour