[Freetype] Another bug in the BDF backend

[Juliusz Chroboczek]

Take 8x13.bdf, and look at the strikes exported by current Freetype
CVS; there is a single strike of size 8x13.  The PCF backend correctly
exports this strike as 13x13.

Recall that the size of a strike is in pixels per em; thus, for square
pixels, the X and Y dimensions should be the same.  The size of a
strike has no relation with the strike's bounding box.

                                        Juliusz