String format specifier error when building on arm32

[m2-farzan]

Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04 on qemu+arm32
• ROS2 Version:
  • Galactic (built from source)
• Version or commit hash:
  • galactic
• DDS implementation:
  • Fast-RTPS

Steps to reproduce issue

Build navigation2 using colcon

Expected behavior

Build successfully

Actual behavior

/root/ros2_galactic_overlay/src/navigation2/nav2_costmap_2d/plugins/inflation_layer.cpp:164:14: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 5 has type ‘std::vector<geometry_msgs::msg::Point_<std::allocator<void> > >::size_type’ {aka ‘unsigned int’} [-Werror=format=]
  164 |     logger_, "InflationLayer::onFootprintChanged(): num footprint points: %lu,"
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  165 |     " inscribed_radius_ = %.3f, inflation_radius_ = %.3f",
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  166 |     layered_costmap_->getFootprint().size(), inscribed_radius_, inflation_radius_);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                          |
      |                                          std::vector<geometry_msgs::msg::Point_<std::allocator<void> > >::size_type {aka unsigned int}
/root/ros2_galactic_overlay/src/navigation2/nav2_costmap_2d/plugins/inflation_layer.cpp:164:77: note: format string is defined here
  164 |     logger_, "InflationLayer::onFootprintChanged(): num footprint points: %lu,"
      |                                                                           ~~^
      |                                                                             |
      |                                                                             long unsigned int
      |                                                                           %u
cc1plus: all warnings being treated as errors
make[2]: *** [CMakeFiles/layers.dir/build.make:76: CMakeFiles/layers.dir/plugins/inflation_layer.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:281: CMakeFiles/layers.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

Additional information

I'll make a PR that fixes this.