Solve some Windows build issues.

* main.c (main): Use ONS(), not OSN().
(prepare_mutex_handle_string) [WINDOWS32]: Use %Ix formatting to
support both 32bit and 64bit systems.
* job.c (free_child, new_job): Use ONS(), not OSN().
* w32/subproc/w32err.c (map_windws32_error_to_string): Use O() when
calling fatal().

Copyright-paperwork-exempt: yes
3 files changed