Fix PR15293: ARM codegen ice - expected larger existing stack allocation

[Stepan Dyatkovskiy]

Renato Golin wrote:
> However, you don't have to waste the registers that are not used because
> of alignment. You can still use them as scratch registers, since they'll
> never be used for argument passing anyway.
So..  should we improve the term of "shadowed registers" then? May be 
create an issue?

-Stepan