message: revert mesh_io.cpp
diff: @@ -3612,6 +3612,8 @@ namespace GEO {
  namespace GEO {
  + GEO::Process::spinlock lock = {0};
  +
  MeshIOFlags::MeshIOFlags() {
  dimension_ = 3;
  attributes_ = MESH_NO_ATTRIBUTES;
  @@ -3624,9 +3626,11 @@ namespace GEO {
  const std::string& filename, Mesh& M,
  const MeshIOFlags& ioflags
  ) {
  + GEO::Process::acquire_spinlock( lock );
  Logger::out("I/O")
  << "Loading file " << filename << "..."
  << std::endl;
  + GEO::Process::release_spinlock( lock );
  M.clear();
  @@ -3676,7 +3680,9 @@ namespace GEO {
  }
  }
  + GEO::Process::acquire_spinlock( lock );
  M.show_stats("I/O");
  + GEO::Process::release_spinlock( lock );
  return true;
  }
  @@ -3685,9 +3691,11 @@ namespace GEO {
  const Mesh& M, const std::string& filename,
  const MeshIOFlags& ioflags
  ) {
  + GEO::Process::acquire_spinlock( lock );
  Logger::out("I/O")
  << "Saving file " << filename << "..."
  << std::endl;
  + GEO::Process::release_spinlock( lock );
  MeshIOHandler_var handler = MeshIOHandler::get_handler(filename);
  if(handler != nil && handler->save(M, filename, ioflags)) {
  