[rfa] mips argument passing fixes for o32

[Andrew Cagney]

Daniel,

Just to close this current thread.  For the moment I'm rejecting the change:

> if (!MIPS_EABI
>                && MIPS_SAVED_REGSIZE < 8
> -              && TARGET_BYTE_ORDER == BIG_ENDIAN
> +              && (TARGET_BYTE_ORDER == BIG_ENDIAN
> +              || TYPE_LENGTH (arg_type) < MIPS_SAVED_REGSIZE)
>                && partial_len < MIPS_SAVED_REGSIZE
>                && (typecode == TYPE_CODE_STRUCT ||
>                typecode == TYPE_CODE_UNION))

I need hard evidence (not comments from GCC) that LE o32 does indead 
left shift small register structs.  I'll probably eventually get that 
evidence however, until then I'd prefer to drop this change.

	Andrew