tdf#81263 ww8par6: only use valid sal_uInt16 values for ULSpace

VerticalOrient position returns a signed SwTwips number,
but ULSpace uses unsigned int16, so negative numbers
were creating huge margins.

fixes commit 3755c87d

Change-Id: I23daea9a913ef73efc42a65e0adfc393eaf4e775
Reviewed-on: https://gerrit.libreoffice.org/32400Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Justin Luth <justin_luth@sil.org>

sw/source/filter/ww8/ww8par6.cxx

@@ -2355,8 +2355,9 @@ bool SwWW8ImplReader::StartApo(const ApoTestResults &rApo,
                 if (aFlySet.HasItem(RES_VERT_ORIENT, &pItem))
                 {
                     const SwFormatVertOrient* pOrient = static_cast<const SwFormatVertOrient*>(pItem);
-                    if (pOrient->GetPos() != 0)
-                        pULSpaceItem->SetUpper(pOrient->GetPos());
+                    SwTwips nPos = pOrient->GetPos();
+                    if( 0 < nPos && nPos <= SAL_MAX_UINT16 )
+                        pULSpaceItem->SetUpper( sal_uInt16(nPos) );
                 }
             }
         }