ffmpeg: enable libvpx support

Signed-off-by: David du Colombier <0intro@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/ffmpeg/ffmpeg.mk

@@ -215,6 +215,13 @@ else
 FFMPEG_CONF_OPT += --disable-vaapi
 endif
 
+ifeq ($(BR2_PACKAGE_LIBVPX),y)
+FFMPEG_CONF_OPT += --enable-libvpx
+FFMPEG_DEPENDENCIES += libvpx
+else
+FFMPEG_CONF_OPT += --disable-libvpx
+endif
+
 ifeq ($(BR2_X86_CPU_HAS_MMX),y)
 FFMPEG_CONF_OPT += --enable-yasm
 FFMPEG_DEPENDENCIES += host-yasm