Thanks for your answer.
ah i think you are experiencing the joys of pd-extended. the solution is simple: just checkout the entire "externals" branch and redo what you have done.
You are right I do use Pd version 0.40.3-extended... What do you mean with "checkout the eternals branch" ? I renamed the directory "Contents/Resources/extra" to "extra_temp", but nothing changed.
there are certainly simpler ways, e.g. copy an existing Makefile for multi-source libraries (e.g. one of tm's iemlib libraries) and adapt it to your needs.
Unfortunately I don't know so much about Makefiles. But shouldn't this basically work with :
akawiiremote.pd_darwin: aka.wiiremote.c wiiremote.c wiiremote.h gcc -o akawiiremote.pd_darwin aka.wiiremote.c wiiremote.c wiiremote.h
(but unfortunately it doesn't)
Thanx,
Florian