Pageant and PuTTYgen About boxes: enlarge to modern size.

Pageant and PuTTYgen About boxes: enlarge to modern size.

The current About boxes are too small to fit in all the buildinfo
data, in particular the source-control commit id. Apparently I forgot
to enlarge them when I enlarged the one in PuTTY proper.

(All the same information is nonetheless *present* in the box, but
there seems to be no way to scroll a static text control, so you can
only find that out by 'Select All' and copying to the clipboard.)

Anyway. Now resized to the same dimensions as the main PuTTY About
box. (Really I should centralise more definitions into a common
resource file, but there we go.)