[Patch, Darwin + doc] alias mconstant-cfstrings to fconstant-cfstrings and document the flag.

[Mike Stump]

On Feb 14, 2011, at 9:05 AM, IainS wrote:
> The Apple system tools expect the "-mconstant-cfstrings" to be "-fconstant-cfstrings".
> 
> the patch below aliases this, for compatibility and provides an entry in invoke.texi
> 
> OK for trunk?

Ok.