building unwind-sjlj.o with / without -fexceptions

[Joern Rennecke]

I find that exception handling doesn't work properly for the epiphany with
recent gcc sources (it worked in the pre-merged port with sources from July).
I suppose that is related to the change mentioned in:
http://gcc.gnu.org/ml/gcc-patches/2011-11/msg01926.html

Looking at the cleanup-5.c failure, I see that _Unwind_ForcedUnwind
calls _Unwind_SjLj_Register, thus we never unwind to where we are supposed
to unwind.

I can fix this in libgcc/config/epiphany/t-epiphany with:

unwind-sjlj.o : CFLAGS += -fno-exceptions
unwind-sjlj.o : c_flags := $(filter-out -fexceptions,$(cflags))

Is that the right way to do it?  Or should we more generally remove  
-fexceptions
from the build rules for the exception handling runtime?