avfilter/vf_blend: add GBRAP16

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/vf_blend.c

@@ -421,7 +421,7 @@ static int query_formats(AVFilterContext *ctx)
         AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8,
         AV_PIX_FMT_YUV420P16, AV_PIX_FMT_YUV422P16, AV_PIX_FMT_YUV444P16,
         AV_PIX_FMT_YUVA420P16, AV_PIX_FMT_YUVA422P16, AV_PIX_FMT_YUVA444P16,
-        AV_PIX_FMT_GBRP16, AV_PIX_FMT_GRAY16,
+        AV_PIX_FMT_GBRP16, AV_PIX_FMT_GBRAP16, AV_PIX_FMT_GRAY16,
         AV_PIX_FMT_NONE
     };