message: simplify: Remove kPreventFlips
  Given the performance impact it seems reasonable for now to always
  enable flip prevention during simplification. We may adjust this in the
  future if there's feedback to the contrary, but for now this simplifies
  the code a bit.
diff: namespace meshopt
  {
  -#ifdef _MSC_VER
  -#pragma warning(disable: 4127) // conditional expression is constant; TODO remove this with kPreventFlips
  -#endif
  -
  -const bool kPreventFlips = true;
  -
  struct EdgeAdjacency
  {
  struct Edge
  @@ -646,12 +640,11 @@ static bool hasTriangleFlips(const EdgeAdjacency& adjacency, const Vector3* vert
  unsigned int b = collapse_remap[edges[i].prev];
  // skip triangles that get collapsed
  - // note: this is mathematically redundant as if either of these is true, the dot product should be 0
  + // note: this is mathematically redundant as if either of these is true, the dot product in hasTriangleFlip should be 0
  if (a == i1 || b == i1)
  continue;
  // early-out when at least one triangle flips due to a collapse
  - // note: since we generally don't expect flips it's not clear if this is better than branchless |=
  if (hasTriangleFlip(vertex_positions[a], vertex_positions[b], v0, v1))
  return true;
  }
  @@ -893,7 +886,7 @@ static size_t performEdgeCollapses(unsigned int* collapse_remap, unsigned char*
  continue;
  }
  - if (kPreventFlips && hasTriangleFlips(adjacency, vertex_positions, collapse_remap, r0, r1))
  + if (hasTriangleFlips(adjacency, vertex_positions, collapse_remap, r0, r1))
  {
  // adjust collapse goal since this collapse is invalid and shouldn't factor into error goal
  edge_collapse_goal++;
  @@ -1329,7 +1322,7 @@ size_t meshopt_simplify(unsigned int* destination, const unsigned int* indices,
  while (result_count > target_index_count)
  {
  - if (kPreventFlips)
  + // note: throughout the simplification process adjacency structure reflects welded topology for result-in-progress
  updateEdgeAdjacency(adjacency, result, result_count, vertex_count, remap);
  size_t edge_collapse_count = pickEdgeCollapses(edge_collapses, result, result_count, remap, vertex_kind, loop);
  