* archive.cc (Library_base::should_include_member): Move
method here from class Archive.
(Archive::Archive): Initialize base class.
(Archive::should_include_member): Move to base class.
(Archive::do_for_all_unused_symbols): New function.
(Add_archive_symbols::run): Remove redundant access to
incremental_inputs.
(Lib_group::Lib_group): Initialize base class.
(Lib_group::do_filename): New function.
(Lib_group::include_member): Pass pointer to Lib_group to
report_object.
(Lib_group::do_for_all_unused_symbols): New function.
(Add_lib_group_symbols::run): Report archive information for
incremental links.
* archive.h (class Library_base): New base class.
(class Archive): Derive from Library_base.
(Archive::filename): Move to base class.
(Archive::set_incremental_info): Likewise.
(Archive::incremental_info): Likewise.
(Archive::Should_include): Likewise.
(Archive::should_include_member): Likewise.
(Archive::Armap_entry): Remove.
(Archive::Unused_symbol_iterator): Remove.
(Archive::unused_symbols_begin): Remove.
(Archive::unused_symbols_end): Remove.
(Archive::do_filename): New function.
(Archive::do_get_mtime): New function.
(Archive::do_for_all_unused_symbols): New function.
(Archive::task_): Move to base class.
(Archive::incremental_info_): Likewise.
(class Lib_group): Derive from Library_base.
(Lib_group::do_filename): New function.
(Lib_group::do_get_mtime): New function.
(Lib_group::do_for_all_unused_symbols): New function.
(Lib_group::task_): Move to base class.
* dynobj.cc (Sized_dynobj::do_for_all_global_symbols): New
function.
* dynobj.h (Sized_dynobj::do_for_all_global_symbols): New
function.
* incremental.cc (Incremental_inputs::report_archive_begin):
Use Library_base; call library's get_mtime; add incremental inputs
entry before members.
(class Unused_symbol_visitor): New class.
(Incremental_inputs::report_archive_end): Use Library_base; use
visitor class to record unused symbols; don't add incremental inputs
entry after members.
(Incremental_inputs::report_object): Use Library_base.
* incremental.h
(Incremental_archive_entry::Incremental_archive_entry): Remove
unused Archive parameter.
(Incremental_inputs::report_archive_begin): Use Library_base.
(Incremental_inputs::report_archive_end): Likewise.
(Incremental_inputs::report_object): Likewise.
* object.cc (Sized_relobj::do_for_all_global_symbols): New
function.
* object.h (Object::for_all_global_symbols): New function.
(Object::do_for_all_global_symbols): New function.
(Sized_relobj::do_for_all_global_symbols): New function.
* plugin.cc (Sized_pluginobj::do_for_all_global_symbols): New
function.
* plugin.h (Sized_pluginobj::do_for_all_global_symbols): New
function.