Don't let ArthurOutputDev be friend of SplashPath anymore

Now that ArthurOutputDev uses Qt glyph rendering, there is
not need for it to be friend of SplashPath anymore.
diff --git a/splash/SplashPath.h b/splash/SplashPath.h
index 81273c6..73dbb63 100644
--- a/splash/SplashPath.h
+++ b/splash/SplashPath.h
@@ -116,8 +116,6 @@
 
   friend class SplashXPath;
   friend class Splash;
-  // this is a temporary hack, until we read FreeType paths directly
-  friend class ArthurOutputDev;
 };
 
 #endif