proposal: fmt/v2: State Flag(int) should be Flag(rune)

<pre>This issue is really just a note.

The Flag method of fmt.State takes an int argument but represents a 'character'.
Probably it should have been changed from int to rune when the rune alias was introduced
(or byte - given all flags are ASCII).

Which version are you using?  (run 'go version')

go1.2</pre>
