[rfa/symtab] Move find_pc_section call to lookup_minimal_symbol_by_pc

[Joel Brobecker]

> (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).)

That makes sense. Will do.

-- 
Joel