* ada-lang.c (ada_lookup_symbol_list_worker): New function, contents
of old ada_lookup_symbol_list. In !full_search case, don't
search superblocks.
(ada_lookup_symbol_list): Delete arg full_search, all callers
updated. Call ada_lookup_symbol_list_worker.
(ada_iterate_over_symbols): Call ada_lookup_symbol_list_worker.
* ada-lang.h (ada_lookup_symbol_list): Update.
* language.h (language_defn): Update comment for
la_iterate_over_symbols.
* linespec.c (iterate_over_file_blocks): New function.
(iterate_over_all_matching_symtabs): Call it.
(lookup_prefix_sym): Ditto.
(get_current_search_block): New function.
(get_search_block): Delete.
(find_label_symbols): Call get_current_search_block.
(add_matching_symbols_to_info): Call iterate_over_file_blocks.
* symtab.c (iterate_over_symbols): Don't search superblocks.