[RFC] Arm frame unwinding directives.

[Paul Brook]

> _Z3fooi:
> 	.unwind_fnbegin
> 	.unwind_save {r4, r7, lr}
>         push    {r4, r7, lr}
>         mov     r7, r8
> 	.unwind_save {r8}
>         push    {r7}
> 	.unwind_setfp sp
>         mov     r7, sp

Typo (I don't have a working compiler for thumb yet).
The last directive should be 
	.unwind_setfp r7, sp

Paul