[ft] Library versioning

[Will Newton]

I have updated the Debian package of FreeType from 2.1.7, where it had been 
for a while, to 2.1.10. This has caused a few problems [1, 2] because a few 
symbols have gone missing - both the API and ABI have changed in this 
respect. The libtool version and soname have remained stable during this 
period, only incrementing the revision, when it would appear that there 
should have been current/age and major/minor changes.

Is this an oversight or have I misunderstood the situation?

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314243
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314385