message: simplify: Add locked collapse stats
  After the simplification completes we gather statistics on the resulting
  edges that can't be collapsed and show the stats by vertex kinds.
diff: @@ -771,6 +771,29 @@ size_t meshopt_simplify(unsigned int* destination, const unsigned int* indices,
  #if TRACE
  printf("passes: %d, worst error: %e\n", int(pass_count), worst_error);
  +
  + size_t locked_collapses[Kind_Count][Kind_Count] = {};
  +
  + for (size_t i = 0; i < index_count; i += 3)
  + {
  + static const int next[3] = {1, 2, 0};
  +
  + for (int e = 0; e < 3; ++e)
  + {
  + unsigned int i0 = result[i + e];
  + unsigned int i1 = result[i + next[e]];
  +
  + unsigned char k0 = vertex_kind[i0];
  + unsigned char k1 = vertex_kind[i1];
  +
  + locked_collapses[k0][k1] += !kCanCollapse[k0][k1];
  + }
  + }
  +
  + for (int k0 = 0; k0 < Kind_Count; ++k0)
  + for (int k1 = 0; k1 < Kind_Count; ++k1)
  + if (locked_collapses[k0][k1])
  + printf("locked collapses %d -> %d: %d\n", k0, k1, int(locked_collapses[k0][k1]));
  #endif
  return index_count;
  