patch: honor volatile bitfield types

[Eric Botcazou]

> doh, you're right.  I was focusing on the movsbl and not the operands
>
> /* { dg-final { scan-assembler "(movb|mov[zs]bl).*bits" } } */
>
> Are there any other ways to load a byte than mobv and mov[sz]bl ?

In my experience, there are only 2 variants of generated code in this area, 
one for i[345]86 and one for i686+, so that's probably good enough.

-- 
Eric Botcazou