check SeekToEndOfRecord for success

Change-Id: I7413a4e9e491b65122eaadb38ad574161f1aa943
(cherry picked from commit d417ffb7)
Reviewed-on: https://gerrit.libreoffice.org/18090Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

filter/source/msfilter/svdfppt.cxx

@@ -2880,7 +2880,9 @@ void SdrPowerPointImport::ImportPage( SdrPage* pRet, const PptSlidePersistEntry*
                                                         insertShapeId( nShapeId, pObj );
                                                 }
                                             }
-                                            aShapeHd.SeekToEndOfRecord( rStCtrl );
+                                            bool bSuccess = aShapeHd.SeekToEndOfRecord(rStCtrl);
+                                            if (!bSuccess)
+                                                break;
                                         }
                                     }
                                 }