* except.c: Lose Unexpected, SetTerminate, SetUnexpected,
TerminateFunctionCall.
(init_exception_processing): Likewise. Terminate et al are now
the fns, not ADDR_EXPRs.
(various): Lose redundant assemble_external calls.
(do_unwind): s/BuiltinReturnAddress/builtin_return_address_fndecl/.