add note on how to reproduce the bug

to be used when `remove_degenerate_faces` will be fixed

Polygon_mesh_processing/test/Polygon_mesh_processing/remove_degeneracies_test.cpp

@@ -6,6 +6,11 @@
 #include <iostream>
 #include <fstream>
 
+//note : when
+//CGAL::get_default_random()::get_seed() = 1473902576
+//the last test (on trihole.off) does not terminate
+//
+
 typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
 
 typedef CGAL::Surface_mesh<K::Point_3> Surface_mesh;