Issues building using nonfree.Dockerfile

[systemmonkey42]

A number of issues occurred with the build.

1 - missing --enable-nonfree option which is now required during builds containing libfdk
2 - missing ${ARTIFACT_DIR} before ${PREFIX} in nonfree.Dockerfile
3 - cp: target '/build/lib' is not a directory needed to create /build/lib directory
4 - rm -f /build/lib/libva-x11.so* failed because the files were not found
5 - error during configure because the command ./configure \cat ${PREFIX}/ffmpeg_configure_options` ` results in the following option

 --nvccflags="-gencode arch=compute_52,code=sm_52"

being split into

• --nvccflags="-gencode
• arch=compute_52,code=sm_52"

This helped

   readarray -t opts < <(xargs -n1 bash -c 'printf -- "%s\n" "$@"' _ < file)
  ./configure "${opts[@]}" \

[systemmonkey42]

This is my diff after I managed to get a working build.

diff.patch.txt