[rfa/symtab] Move find_pc_section call to lookup_minimal_symbol_by_pc

[Andrew Cagney]

>  > > +  if (ecs->stop_func_name == NULL
>  > > +      && step_over_calls == STEP_OVER_UNDEBUGGABLE)
>  > > +    {
>  > > +      /* We couldn't determine where we stopped, so we just stepped
>  > > +         inside undebuggable code.  Since we want to step over this
>  > > +         kind of code, we keep going until the inferior returns from
>  > > +         the current function.  */
>  > > +      handle_step_into_function (ecs);
>  > > +      return;
>  > > +    }
>  > 
>  > not triggering.  ->stop_func_name had a non-NULL but bogus symbol name.
> 
> So, the complete fix includes Joel's patch?

Not really.  It was only by seeing Joel's change, and hence knowing that 
edge case, that I had a fighting chance of figuring out how it was ment 
to work.  BTW, even though "step_over_calls == STEP_OVER_UNDEBUGGABLE" 
is technically redundant, I think it is needed - clarifies this specific 
condition.

(Joel, perhaphs write the above as:
step_over_calls == STEP_OVER_UNDEBUGGABLE && cs->stop_func_name == NULL
since that is how the test is ordered elsewhere (since neither has a 
sideeffect it's no real difference).)

>> ok?
> 
> sure, let's see what other obscure cases break now. :-)

In it goes ...

Andrew