lavc: mark deprecated AVCodec.max_lowres for removal on next bump

libavcodec/avcodec.h

@@ -2706,7 +2706,9 @@ typedef struct AVCodec {
     const int *supported_samplerates;       ///< array of supported audio samplerates, or NULL if unknown, array is terminated by 0
     const enum AVSampleFormat *sample_fmts; ///< array of supported sample formats, or NULL if unknown, array is terminated by -1
     const uint64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
+#if FF_API_LOWRES
     attribute_deprecated uint8_t max_lowres; ///< maximum value for lowres supported by the decoder
+#endif
     const AVClass *priv_class;              ///< AVClass for the private context
     const AVProfile *profiles;              ///< array of recognized profiles, or NULL if unknown, array is terminated by {FF_PROFILE_UNKNOWN}