Bug#932245: Build system updated

[Norbert Schlia]

After a few attempts I upgraded the build system to the latest Debian 10 
and now I got rid of all errors and many warnings. There are still a few 
glitches, but I don't think they are too important. There's a newer 
version of ffmpegfs, but I don't want to switch to it yet to avoid newer 
bugs. Also I'll have to figure out how to get the gpg signature check up.

Anyone out there willing to sponsor me? If you love music and have it 
available as video and audio files on disk you gotta try it out. It's a 
nice and convenient tool to get the stuff avialable anywhere, on your 
mobile phone, iPad or whatever. It bundles the full power of FFmpeg to 
do so. I am using it myself to provide my files to my Android phone.