Just to get the libdroidmedia.so, I didn’t follow the HADK pdf. Maybe it’s wrong by the way. But just having the Android sources, and compile there was enough.
For lunch, I just type the TAB key for autocompletion, and took the value that corresponds to my device (here a xqau52, its written on the back of the phone, for a 10ii device at least).
Then, the make target is libdroidmedia, not droidmedia.