package/mplayer: Fix linking with libvorbis/libdvdread

Fixes
http://autobuild.buildroot.net/results/7f6/7f6e5396e95a3c3b676ca59bedc5317aa88e5f4c/
http://autobuild.buildroot.net/results/6ac/6acd9cf25c3088d313247510db47a214fff30c67/
http://autobuild.buildroot.net/results/a0d/a0da41bb734dbcdb17e13d852cfbdba5e069429e/
http://autobuild.buildroot.net/results/d0c/d0caf60c1ddf4e05086c93f646e32b5ddc75b6ce/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Reviewed-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Tested-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>