* common/config/or1k/or1k-common.c:
  (TARGET_EXCEPT_UNWIND_INFO) define.
  (or1k_except_unwind_info) use DWARF2 unwind info as default
  but support SJLJ if forced with --enable-sjlj-exceptions.
  * config/or1k/or1k-protos.h:
  (or1k_expand_pic_symbol_ref) removed unneeded ATTRIBUTE_UNUSED.
  (or1k_eh_return_handler_rtx) defined prototype (body in or1k.c).
  (or1k_return_addr_rtx) defined prototype (body in or1k.c).
  * config/or1k/or1k.c:
  (or1k_save_reg_p) save stack pointer when frame pointer is not saved.
  (or1k_save_reg_p) save registers used with eh_return.
  (or1k_expand_epilogue) do not restore link register if we are
  returning from eh_return.
  (or1k_expand_epilogue) apply EH stack adjustment to stack pointer.
  (or1k_eh_return_handler_rtx) eh_return should write to the link register.
  (or1k_return_addr_rtx) in the case of GOT the link register cannot be read
  after the prologue. in this case, use the stored link register from the
  stack frame.
  (or1k_frame_pointer_required) require FP in eh_return and
  when alloca is used.
  (TARGET_FRAME_POINTER_REQUIRED) define.
  * config/or1k/or1k.h:
  (INITIAL_FRAME_POINTER_OFFSET) not used, removed.
  (RETURN_ADDR_RTX) define.
  (EH_RETURN_REGNUM) define. use reg 23.
  (EH_RETURN_DATA_REGNO) define. use reg 25, 27, 29 and 31.
  (EH_RETURN_STACKADJ_RTX) define.
  (EH_RETURN_HANDLER_RTX) define.