avcodec/Makefile: Remove superfluous avformat->DNXHD dependencies

There is no mxfenc dependency any more since commit
b9a26b9d.
Also remove a dnxhddata.h inclusion in mxfenc that was forgotten
in the very same commit.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/Makefile

@@ -983,14 +983,12 @@ OBJS-$(CONFIG_VP8_QSV_HWACCEL)            += qsvdec.o
 OBJS-$(CONFIG_ISO_MEDIA)               += mpeg4audio.o mpegaudiodata.o
 
 OBJS-$(CONFIG_ADTS_MUXER)              += mpeg4audio.o
-OBJS-$(CONFIG_DNXHD_DEMUXER)           += dnxhddata.o
 OBJS-$(CONFIG_FITS_DEMUXER)            += fits.o
 OBJS-$(CONFIG_LATM_MUXER)              += mpeg4audio.o
 OBJS-$(CONFIG_MATROSKA_AUDIO_MUXER)    += mpeg4audio.o
 OBJS-$(CONFIG_MATROSKA_MUXER)          += mpeg4audio.o
 OBJS-$(CONFIG_MOV_DEMUXER)             += ac3tab.o
 OBJS-$(CONFIG_MATROSKA_DEMUXER)        += mpeg4audio.o
-OBJS-$(CONFIG_MXF_MUXER)               += dnxhddata.o
 OBJS-$(CONFIG_NUT_MUXER)               += mpegaudiodata.o
 OBJS-$(CONFIG_RTP_MUXER)               += mpeg4audio.o
 OBJS-$(CONFIG_SPDIF_MUXER)             += dca.o

libavformat/mxfenc.c

@@ -48,7 +48,6 @@
 #include "libavutil/pixdesc.h"
 #include "libavutil/time_internal.h"
 #include "libavcodec/bytestream.h"
-#include "libavcodec/dnxhddata.h"
 #include "libavcodec/dv_profile.h"
 #include "libavcodec/h264_ps.h"
 #include "libavcodec/golomb.h"