fix crash on export of ooo30155-1.sxw to odt

Change-Id: I1dd087ea6803f29756e1b78385a4a98f7378e616

basegfx/source/polygon/b2dpolygontools.cxx

@@ -662,7 +662,7 @@ namespace basegfx
                     // is checked above. Unfortunately, with floating-
                     // point calculations, this case might happen.
                     // Handled by nIndex check below
-                    if(nIndex < nEdgeCount && fTools::moreOrEqual(fDistance, fEdgeLength))
+                    if (nIndex+1 < nEdgeCount && fTools::moreOrEqual(fDistance, fEdgeLength))
                     {
                         // go to next edge
                         fDistance -= fEdgeLength;