Cleanup code related to --identify option.

Cleanup code related to --identify option.

        * binutils/dlltool.c (file scope): Removed globals identify_ms,
        identify_member_contains_symname_result,
        identify_dll_name_list_head, and identify_dll_name_list_tail.
        Renamed existing typedef dll_name_list_type to
        dll_name_list_node_type.
        Added new typedefs dll_name_list_type, symname_search_data_type,
        and identify_data_type.
        (identify_append_dll_name_to_list): Renamed to...
        (dll_name_list_append): ...here.  Changed signature to accept list
        argument rather than use global.
        (identify_count_dll_name_list): Renamed to...
        (dll_name_list_count): ...here.  Changed signature to accept list
        argument rather than use global.
        (identify_print_dll_name_list): Renamed to...
        (dll_name_list_print): ...here.  Changed signature to accept list
        argument rather than use global.
        (identify_free_dll_name_list): Renamed to...
        (dll_name_list_free_contents): ...here.
        (dll_name_list_free): New function.
        (dll_name_list_create): New function.
        (identify_process_section_p): Changed signature to accept
        ms_style_implib argument rather than use global.
        (identify_member_contains_symname): Expect incoming void * data to
        be symname_search_data_type.
        (identify_dll_for_implib): Use new functions dll_name_list_create
        and dll_name_list_free.  Use new types symname_search_data_type
        and identify_data_type to communicate with search routines.
        (identify_search_section): Expect incoming void * data to be
        identify_data_type. Use its contents rather than global
        variables.