Using Autobuild leads to a working TVHeadend.
But I did not manage to activate libfdkaac. I've installed the apt packages libfdk-aac-dev and libfdk-aac2. Afterwards I've run
ldconfig -p | grep libfdk-aac
libfdk-aac.so.2 (libc6,x86-64) => /lib/x86_64-linux-gnu/libfdk-aac.so.2
libfdk-aac.so (libc6,x86-64) => /lib/x86_64-linux-gnu/libfdk-aac.so
So, I think I have correctly installed these libs. ./configure still says the features libfdkaac and libfdkaac_static are disabled. What went wrong?