nasm-2.13.01 is incompatible with the default debian/buster gcc version 8.3.0 (Debian 8.3.0-6)
I was able to successfully compile after updating build.sh to nasm-2.14.02 as per the official FFmpeg CompilationGuide/Ubuntu
https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu
nasm-2.13.01 is incompatible with the default debian/buster gcc version 8.3.0 (Debian 8.3.0-6) I was able to successfully compile after updating build.sh to nasm-2.14.02 as per the official FFmpeg CompilationGuide/Ubuntu https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu