mplayer: convert to gentargets, bump to a recent SVN version

Based on the conversion to gentargets done by Martin Banky, several
issues were fixed, and the mplayer package was improved:

 * Updated to a recent SVN version

 * Removed mandatory dependency on libmad

 * The AVR32 specific patch has been removed. It was a pain to remain
   blocked at the old 1.0-rc2 just for this patch. All this
   optimization work should have been submitted upstream, Buildroot is
   not the place to carry such heavy modifications.

 * Options were added to select whether mplayer and/or mencoder should
   be built/installed.

 * Support for additional options if packages have been selected:
   tremor, libmad, libtheora, libpng, jpeg, xlib_libX11,
   xlib_libXv. More could be added in the future.

 * Support for ARM-related optimization options. Similar improvements
   could be done for x86 and PowerPC architectures.

[Peter: fix build with !IPV6]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>