Fix TTC parsing

[GoogleCodeExporter]

I have no idea how to submit patches, so forgive me if this is an inappropriate 
venue.

Attached is a patch fixing TTC parsing.
The constant 12 was hardcoded instead of using `offset`.

Tested on a TTC v2.0 file, I don't have a v1.0 file to test on but based on 
what I understand of the file format I don't think there should be any issues 
with that.

Original issue reported on code.google.com by magician...@gmail.com on 10 Sep 2014 at 4:30

Attachments:

• freetype-go.patch