error with ubuntu18.04 ffmpeg4.1

[714273725]

I copy your build script and only change the ffmpeg version to 4.1
can you help me to fine what's wrong?
..................
/home/gjy/ndk/android-ndk-r16b-linux-x86_64/android-ndk-r16b/toolchain/arm/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: cannot find -lharfbuzz
/home/gjy/ndk/ffmpeg-4.1/temp/lib/libfreetype.a(autofit.o):/home/gjy/ndk/ffmpeg-4.1/freetype/src/autofit/autofit.c:function af_cjk_metrics_init: error: undefined reference to 'hb_buffer_create'
..................

[bolds07]

you are having problem related to libfreetype... you can either try to upgrade your ndk to latest or comment the libfreetype support in the build script