ImageFont.truetype: error in windows fonts fallback

There is a small issue in Windows fall back in ImageFont.truetype (lines 246-248)

```
if windir:
    filename = os.path.join(windir, "fonts", font)
    return FreeTypeFont(font, size, index, encoding)
```

Second line should read 

```
return FreeTypeFont(filename, size, index, encoding)
```

(PIL-1.1.7 has this right)
