__pad_char and PR3655

[Paolo Carlini]

Hi all,

I investigated a little bit PR3655 and my first impression is that the helper function
__pad_char in ostream.tcc could be appreciably simplified, thus easing the fix of the PR
and cleaning up the library.

AFAICT this function is called only from ostream.tcc members, so I'm not sure if it is
being touched by Benjamin as part of its ongoing work.

It is?

Cheers,
Paolo.