Factorise the Video Control code. List all available controls in debug messages. Add a callback to update those we already support on the flag (doesn't work properly yet, it might need a restart or something and people on #v4l aren't really helpfull).

Don't compile any of the alsa audio input code if HAVE_ALSA isn't defined. This mainly removes the --v4l2-alsa option if alsa devlopement headers aren't available.

MacOSX/Framework: Minimizes Package Size. only copy the libraries that the vlc modules need. (Patch by Enrique Osuna).

Adds libgcrypt.m4 for systems running autotools without libgcrypt-dev installed
Prefers tabs over spaces in Makefiles