package/mplayer: add optional dependencies to libgl, libvpx and opus

Mplayer links to these packages when present:

output/host/usr/bin/x86_64-linux-readelf -a output/target/usr/bin/mplayer | grep NEEDED | grep "opus\|vpx\|GL"
 0x0000000000000001 (NEEDED)             Shared library: [libopus.so.0]
 0x0000000000000001 (NEEDED)             Shared library: [libvpx.so.2]
 0x0000000000000001 (NEEDED)             Shared library: [libGL.so.1]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/mplayer/mplayer.mk

@@ -231,9 +231,12 @@ MPLAYER_CONF_OPTS += --disable-liblzo
 endif
 
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_BZIP2),bzip2)
+MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_HAS_LIBGL),libgl)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_LIBTHEORA),libtheora)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_LIBPNG),libpng)
+MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_LIBVPX),libvpx)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_JPEG),jpeg)
+MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_OPUS),opus)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_XLIB_LIBX11),xlib_libX11)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_XLIB_LIBXEXT),xlib_libXext)
 MPLAYER_DEPENDENCIES += $(if $(BR2_PACKAGE_XLIB_LIBXINERAMA),xlib_libXinerama)