[02/12] Add fesetexcept: aarch64

[Paul Eggert]

Thanks, that patch series looks good, though I have one minor question and/or 
quibble.

> +  if (fpsr != fpsr_new)
> +    _FPU_SETFPSR (fpsr_new);

I assume that the 'if (fpsr != fpsr_new)' is present purely for performance 
reasons, i.e., that the code would be correct if '_FPU_SETFPSR (fpsr_new)' were 
executed unconditionally. Are practical programs likely to see a performance 
improvement because of the 'if (fpsr != fpsr_new)'? My guess is no, because 
typically programs will use fesetexcept to change settings. If my guess is 
right, I'd omit the 'if (fpsr != fpsr_new)' test, on the grounds of simplicity.

Similarly for arm, hppa, powerpc.