Log Message:
go-ttf: update to 2.008

Change pkgsrc versioning scheme to match upstream's.

Bigelow & Holmes have prepared new versions of the Go Fonts. The version
numbers have changed from 2.004 to 2.008. ChangeLog:

* New! 2 new fonts, bringing the total to 12: Go Smallcaps and Go
  Smallcaps Italic.
* New! U+FFFD REPLACEMENT CHARACTER glyph added.
* U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE ring tweaked.
* U+00F0 LATIN SMALL LETTER ETH glyph lightened.
* Superfluous U+0005 <control> glyph removed.
* Split integral, chart draw, block, shade and related glyphs now span
  the full height and have fewer seams when tiled.
* Raised most capital letter diacritics and some lowercase diacritics.
* Mono character widths fixed to be uniform.
* Underline position adjusted.
* SFNT glyph order and cmap table optimized.
* SFNT glyph names (post table) regularized, consistent with the AGLFN.
* ttfautohint upgraded to the latest version, from 1.5 to 1.6.