Unfortunatley I can't reproduce your problem as I have a different system (Windows, avr-gcc 4.3.2), which obviously doesn't have this problem.
A basic, general tip: Run the same build command without the -s; the actually used compiler and linker command lines will become apparent in the console output and if you compare them with the online help of these tools you might get a step ahead. Then copy the critical command line and enter them directly in the shell to see if you can reproduce the same error. If so, you can start manipulating the command line until you get the linker succeesfully run or let it at least print more meaningful messages.
If the printed error messages were literally correct all you'd to do is to remove the three options from the command line; none of them is essential. (Although it could indeed be just a matter of differences in the linker interface of our two versions, I don't really believe so. I'd rather guess that the reported problem is a subsequent fault and that you will have to find the true problem.)
Given, you've found a properly working linker command line it's straight forward to change the makefiles so that they adopt your findings. Open file makefile/compileLinkAndUpload.mk and change the definition of variable lFlags. Look for "Linking project".
And please let us know ...
P.S. Please note, that this topic refers to the first release of RTuinOS (0.9). Meanwhile, version 1.0 has been released. If you still work with the first release, the first thing you should do is to download, install and try the current revision. Please visit http://forum.arduino.cc/index.php?topic=184593.0
to get more information