libffmpeg: fix duplicated ffjni

tools/mklibffmpeg.sh

@@ -50,6 +50,7 @@ DUP_OBJS=(libswscale/log2_tab.o libswresample/log2_tab.o libavcodec/log2_tab.o l
  libavformat/mpeg4audio_sample_rates.o
  libavformat/rangecoder_dec.o
  libavformat/jpegxl_parse.o # what if jpegxl parser is disabled? remove 1 if both libavcodec and libavformat has jpegxl_parse.o
+ libavformat/ffjni.o
  libavutil/avutilres.o
  libavcodec/avcodecres.o
  libavcodec/half2float.o # half2float.c is in libavutil, but not built into libavutil, always built in swscale