• Use xo_warn() / xo_err() instead of warn() / err().

• Add a test case for the POSIX-mandated stdout error check.

• While here, don't assume the size of off_t, address some style issues, and broaden the use of bool instead of int.

• Reorder SEE ALSO section.

MFC after: 1 week
Sponsored by: Klara, Inc.