modules/genmf: Use printf instead of echo -n to prevent some weird shell/Makefile issues. (Fix make install on Mac OS X).

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.