RFA: new gdbarch methods for inserting/removing breakpoints

[Andrew Cagney]

Kevin Buettner wrote:
> 
> Andrew, et.al,
> 
> I would like to check in the changes below.  These changes will allow
> us to write architecture specific versions of
> memory_insert_breakpoint() and memory_remove_breakpoint().  Custom
> versions of these functions are needed on architectures where an
> instruction is a strange size and/or does not fall neatly on a
> byte-aligned boundary.  (E.g, ia64.)

Should ``default_memory_insert_breakpoint'' be made the default so that
other targets continue to work?
I may have missed it?

> I'll add some documentation to doc/gdbint.texinfo after approval.

I'll arange for someone to stand over you until you do this :-)

	Andrew