[RFA] gdb-events.sh: selected-frame-level-changed event

[Andrew Cagney]

> Hi,
> 
> MI uses GDB's frame level to track a user's view of the current stack. As 
> you can imagine, this is tightly coupled to the console's stack commands 
> ("up", "down", and "frame").
> 
> This event notifies clients when the stack frame level has been changed, 
> allowing all the UIs to remain in sync wrt the stack view.
> 
> I'll submit the stack.c changes separately, since the exact meaning
> of this event may be open to interpretation.

Ok.

Any thoughts on how selected-thread events will be handled?  They also 
change the selected-fraome.

Andrew