Can't debug x86_64 C++ programs.

[John Fine]

John Fine wrote:
> I set a breakpoint inside architecture_changed_event (in gdb-events.c) 
> on the line
>  if (!current_event_hooks->architecture_changed)
> and I verified that current_event_hooks->architecture_changed is equal 
> to zero, so architecture_changed_event does nothing.
Oops.  That was sloppy debugging on my part.  
current_event_hooks->architecture_changed is equal to zero the first 
time architecture_changed_event is called.  But 
architecture_changed_event is called again later and 
current_event_hooks->architecture_changed then points to 
gdbtk_architecture_changed, which calls Tcl_Eval(gdbtk_interp, 
"gdbtk_tcl_architecture_changed");

That still doesn't end up calling setup_architecture_data.  I don't know 
whether I can debug well enough to find out why.