building unwind-sjlj.o with / without -fexceptions

[Joern Rennecke]

Quoting Richard Henderson <rth@redhat.com>:

>> 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?
>
> No.  In general removing -fexceptions from the unwind routines will cause
> the unwind routines to fail.

Is this something where dwarf2 unwinding diverges from sjlj exception  
handling?
Or can you show a testcase where -fexceptions is needed for
unwind-sjlj.o ?
The above patch makes hundreds of failures in the g++ and libstdc++-v3
testsuite go away, with no unwind related failures remaining.