Make sure VLC.app doesn't take too much time to build. This breaks VLC-release.app, and following commit will fix that.

This avoids an infinite recursion if vlc_mutex_* fails (calls msg_Err).

macosx: added an extra sanity check to fix video playback on Macs using the QT4 interface (fullscreen mode still broken)

 - Use inlines for expansion safety.

contribs: added an optional entry to compile QT4 on Darwin. run 'make .qt4_mac', if you want to build it. Note that you'll need to type 'yes' shortly afterwards to accept Qt's GPL. I'll provide a patch for this.

Qt4 - tracks detection is splitted from the other functions. Fix the "fullscreen button not showing" bug in some cases.