Change printf format string to include the extra blank

This is a follow up change to r364321 after a discussion about the style.
All near by places use extra blanks in format strings, and while use of the
format string to provide the extra blank may need more cycles than adding 1
to twidth, it generates shorter code and is clearer in the opinion of some
reviewers of the previous change.

Not objected to by: emaste
MFC after: 3 days