RFA [Patch]: Update defintion of STRUCTURE_SIZE_BOUNDARY

[Andrew Pinski]

> 
> Hi Guys,
> 
>   The definition of STRUCTURE_SIZE_BOUNDARY in libobjc/encoding.c needs
>   to be constant, but it currently depends upon the definition of
>   BITS_PER_UNIT which is not defined by default.  The patch below adds
>   a default definition in case one is not supplied by the target.
> 
>   OK to apply ?
This is fine.

Thanks,
Andrew Pinski