Hm, functions? I guess it cant find a contrib and tries to create a kind of standard init-script. As its rather simple, you can just copy any *IX-flavoured init-script and adopt.
I havent ever heard of that /etc/init.d/functions file, but Im sure it pertains to some specific linux-flavour.
My Ubuntu machine doesnt have that file, neither does my slug. *shrug*
What part of mt-daapd is referencing this?
If it built successfully, is it prolly the init-script itself?