[Patch] Move Objective-C runtime flags to modern options system.

[Mike Stump]

On Nov 9, 2011, at 10:12 AM, Iain Sandoe wrote:
> This puts "flag_next_runtime" into the global options structure

> I needed to deal with '-fobjc-sjlj-exceptions'   and elected to remove it -
> - this is because there is only one valid exception model for each permutation of runtime and ABI - thus the User flag is just clutter.
> 
> It is now ignored as a User flag - and the relevant selection actions are all local to Objective C.
> 
> (yay! got rid of one exceptions-related flag :-)) ....

Yeah, that sounds like a good idea.

> +ObjC ObjC++ Ignore Warn(switch %qs has been removed and is set automaticaly where required)

Spelling, automatically.

> +    targetting Darwin.  However, the flag overrides have not be called yet.  */

Spelling, targeting.

> +  if (flag_objc_exceptions)
> +    /* ??? Should we warn that this is incompatible, if the user has set it.
> +       For now, just force it it off.  */
> +    flag_exceptions = 0;

Where was this in the previous code?  In ObjC++, exceptions can be on for C++ and should not be turned off.  Does this code ever turn off C++ exceptions?

As a stylistic note, I'd rather have a literal translation into the new mechanism, no changes to behavior, and then a separate patch that then changes things you think are wrong or could be done better.  The first is large and mechanical and it important to get right.  The follow-on patches, when done one at a time, if any one proved wrong, it alone could then be reverted.

If the flag_exceptions = 0 bit and Joseph's comments are fixed, I think we're done.