[RFA] make first parameter of to_lookup_symbol const char *

[Joel Brobecker]

> delete target_ops.to_lookup_symbol
> 
> gdb/ChangeLog:
> 
>         * target.h (struct target_ops): Remove to_lookup_symbol field.
>         (target_lookup_symbol): Delete macro.
>         * target.c (nosymbol, debug_to_lookup_symbol): Delete.
>         (update_current_target, setup_target_debug): Remove handling
>         of to_lookup_symbol target_ops field.
>         * ada-tasks.c (get_known_tasks_addr): Remove use of
>         target_lookup_symbol.
>         * coffread.c (coff_symtab_read): Likewise.
>         * dbxread.c (read_dbx_symtab): Ditto.

Thanks to everyone for the review and feedback.  I checked this patch in.

-- 
Joel