Turns out we are using a single FT_Face object for a given font size throughout the
app_server - but the FT_Face object is not designed for a multi-threaded access, AFAICT.
For example, it only has a single glyph slot, that we were using from different threads.
This fix does not cover the renderer, however, which also uses that shared object; IOW
even though it will crash less often it will still crash because of this.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@14543 a95241bf-73f2-0310-859d-f6bbb57e9c96
c2a52d2836