MacOS is currently using one of our custom "hourglass" cursors during
busy times. This PR changes it to an OS-supplied cursor, a pointer
arrow with an animated blue spinner, meant for this purpose. Although
undocumented it has been used by many applications for many years.
Including Firefox for 11 years now.
Pull Request: https://projects.blender.org/blender/blender/pulls/136735
8325e7f5e4