avcodec/v4l2: fix compile with older videodev2.h

Some of these symbols are only defined in newer kernel releases.
Signed-off-by: Aman Gupta <aman@tmm1.net>

libavcodec/v4l2_buffers.c

@@ -351,10 +351,18 @@ static int v4l2_buffer_swframe_to_buf(const AVFrame *frame, V4L2Buffer *out)
     switch (pixel_format) {
     case V4L2_PIX_FMT_YUV420M:
     case V4L2_PIX_FMT_YVU420M:
+#ifdef V4L2_PIX_FMT_YUV422M
     case V4L2_PIX_FMT_YUV422M:
+#endif
+#ifdef V4L2_PIX_FMT_YVU422M
     case V4L2_PIX_FMT_YVU422M:
+#endif
+#ifdef V4L2_PIX_FMT_YUV444M
     case V4L2_PIX_FMT_YUV444M:
+#endif
+#ifdef V4L2_PIX_FMT_YVU444M
     case V4L2_PIX_FMT_YVU444M:
+#endif
     case V4L2_PIX_FMT_NV12M:
     case V4L2_PIX_FMT_NV21M:
     case V4L2_PIX_FMT_NV12MT_16X16:

libavcodec/v4l2_m2m_enc.c

@@ -245,8 +245,10 @@ static int v4l2_send_frame(AVCodecContext *avctx, const AVFrame *frame)
     V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;
     V4L2Context *const output = &s->output;
 
+#ifdef V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME
     if (frame && frame->pict_type == AV_PICTURE_TYPE_I)
         v4l2_set_ext_ctrl(s, MPEG_CID(FORCE_KEY_FRAME), 0, "force key frame");
+#endif
 
     return ff_v4l2_context_enqueue_frame(output, frame);
 }