[pkg-fgfs-crew] Bug#743169: osgDB_freetype.so no longer built

[Rebecca N. Palmer]

Control: reassign -1 openscenegraph
Control: retitle -1 osgDB_freetype.so no longer built

This bug does exist in Ubuntu Trusty and Debian sid, but not when the 
same version of openscenegraph+flightgear are built in Ubuntu Saucy, and 
is due to osgDB_freetype.so (the plugin that loads this file type) not 
being built.

The freetype headers have moved (from /usr/include/freetype2/freetype to 
/usr/include/freetype2), and openscenegraph's build system bypasses 
freetype's normal find mechanism (see 
OpenSceneGraph/CMakeModules/FindFreeType.cmake).

(To avoid similar problems in future, you may want to make the build 
fail instead of silently disabling plugins: see #726487 for one way to 
do this.)