ffmpeg: add patch - backport HEVC10 support

packages/multimedia/ffmpeg/patches/ffmpeg-99.999-backport-hevc10bit.patch

@@ -0,0 +1,24 @@
+From fb37da37ac1e17f643269ea5bad5bee7e79dcb3a Mon Sep 17 00:00:00 2001
+From: Jean-Yves Simon <lethalwp@gmail.com>
+Date: Tue, 9 Aug 2016 17:15:30 +0200
+Subject: [PATCH] avcodec/hevc: Add YUV420P10 to vaapi hardware decode -
+ permits hardware decoding of HEVC Main 10 on AMD RX 480
+
+Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
+---
+ libavcodec/hevc.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/libavcodec/hevc.c b/libavcodec/hevc.c
+index cb1263c..764e093 100644
+--- a/libavcodec/hevc.c
++++ b/libavcodec/hevc.c
+@@ -370,6 +370,9 @@ static int set_sps(HEVCContext *s, const HEVCSPS *sps, enum AVPixelFormat pix_fm
+ #if CONFIG_HEVC_D3D11VA_HWACCEL
+         *fmt++ = AV_PIX_FMT_D3D11VA_VLD;
+ #endif
++#if CONFIG_HEVC_VAAPI_HWACCEL
++        *fmt++ = AV_PIX_FMT_VAAPI;
++#endif
+         break;
+     }