message: simplify: Minor cleanup
  Use sizeof(float)*3 instead of 12.
diff: @@ -117,7 +117,7 @@ struct PositionHasher
  bool equal(unsigned int lhs, unsigned int rhs) const
  {
  - return memcmp(vertex_positions + lhs * vertex_stride_float, vertex_positions + rhs * vertex_stride_float, 12) == 0;
  + return memcmp(vertex_positions + lhs * vertex_stride_float, vertex_positions + rhs * vertex_stride_float, sizeof(float) * 3) == 0;
  }
  };
  