[cairo] Simple cairo-trace printing cleanups

[Carl Worth]

Hi Chris,

Here are two tiny patches to adjust what cairo-trace prints to
stdout/stderr. It removes some prints about FT_Open_Face and
adds a print of the filename actually logged to.

I would have just pushed without asking, but I wanted to check
if the FT_Open_Face messages were anything more than leftover
debug code that's just not needed anymore.

Let me know and I'll be glad to push,

-Carl