Ok, removing the string from both Makefiles did the trick, many thanks for your quick answer!
I am been able to build the binary to run in command-line style and now I am testing FS-UAE on my dual G4 MDD machine.
Since it is a relatively old system I need to experiment some fine tuning in emulation parameters (expecially in the audio part) but I am quite happy about the first results: simply the best Amiga emulation around and now for the PowerMacs too!
Thank you!