Fix LTO vs. COFF archives

Fix LTO vs. COFF archives

Avoid scan of symbols on objects in coff archives since we don't need
to do anything special with common symbols.  The scan is quite useless,
and breaks LTO due to slim LTO objects not having symbols available
until after the plugin has claimed them.  Instead we can add objects
based on their archive symbol map.

Also, rip out the archive symbol hash table used by the generic
linker.  Using a hash breaks one feature of unix archive linking;
The first object file in an archive defining any given symbol should
be the object extracted to satisfy that symbol.  What's more a hash
isn't much faster except in pathological cases where object file
ordering causes many scans of the archive.  See the comment which I'm
removing from elf_link_add_archive_symbols.

Finally, tidy elflink.c archive handling a little.

	PR 13557
	* linker.c (struct archive_list, struct archive_hash_entry,
	struct archive_hash_table, archive_hash_newfunc,
	archive_hash_table_init, archive_hash_lookup, archive_hash_allocate,
	archive_hash_table_free): Delete.
	(_bfd_generic_link_add_archive_symbols): Add h and name params to
	checkfn.  Rewrite using a straight-forward scan over archive map.
	(generic_link_check_archive_element_no_collect,
	generic_link_check_archive_element_collect,
	generic_link_check_archive_element): Add h and name params.
	* aoutx.h (aout_link_check_archive_element): Likewise.
	* pdp11.c (aout_link_check_archive_element): Likewise.
	* xcofflink.c (xcoff_link_check_archive_element): Likewise.
	* cofflink.c (coff_link_check_archive_element): Likewise.  Don't
	scan symbols, simply add archive element whenever h is undefined.
	(coff_link_check_ar_symbols): Delete.
	* ecoff.c (read_ext_syms_and_strs): Delete.
	(reread_ext_syms_and_strs): Delete.
	(ecoff_link_check_archive_element): Add h and name param.  Don't
	scan symbols, simply add based on h.  Use ecoff_link_add_object_symbols.
	* elflink.c (elf_link_is_defined_archive_symbol): Don't test
	archive_pass.
	(elf_link_add_archive_symbols): Delete "defined" array, merge
	functionality into "included".  Make "included" a char array.  Don't
	set or test archive_pass.
	* libbfd-in.h (_bfd_generic_link_add_archive_symbols): Update.
	* libbfd.h: Regenerate.