Enable 64-bit archives in ar and ranlib

Since existing ld and gold support the 64-bit (MIPS) ELF archives, we
can use the 64-bit (MIPS) ELF archives as 64-bit archives.  Since the
plugin target is used to create archive in plugin-enabled ar, we need
a way to enable 64-bit archives in the plugin target.  This patch adds
--enable-64-bit-archive to bfd to force 64-bit archives in ar and
ranlib.  Since both 64-bit MIPS and s390 ELF targets currently use
64-bit archives, 64-bit archives are enabled by default for them.
64-bit archive is generated automatically if the archive is too big.

Tested on Linux/x86 and Linux/x86-64 with existing ld and gold.

bfd/

	PR binutils/14625
	* archive.c (bfd_slurp_armap): Replace
	bfd_elf64_archive_slurp_armap with
	_bfd_archive_64_bit_slurp_armap.
	(bsd_write_armap): Call _bfd_archive_64_bit_write_armap if
	BFD64 is defined and the archive is too big.
	(coff_write_armap): Likewise.
	* archive64.c (bfd_elf64_archive_slurp_armap): Renamed to ...
	(_bfd_archive_64_bit_slurp_armap): This.
	(bfd_elf64_archive_write_armap): Renamed to ...
	(_bfd_archive_64_bit_write_armap): This.
	* configure.ac: Add --enable-64-bit-archive.
	(want_64_bit_archive): New.  Set to true by default for 64-bit
	MIPS and s390 ELF targets.
	(USE_64_BIT_ARCHIVE): New AC_DEFINE.
	* config.in: Regenerated.
	* configure: Likewise.
	* elf64-mips.c (bfd_elf64_archive_functions): Removed.
	(bfd_elf64_archive_slurp_armap): Likewise.
	(bfd_elf64_archive_write_armap): Likewise.
	(bfd_elf64_archive_slurp_extended_name_table): Likewise.
	(bfd_elf64_archive_construct_extended_name_table): Likewise.
	(bfd_elf64_archive_truncate_arname): Likewise.
	(bfd_elf64_archive_read_ar_hdr): Likewise.
	(bfd_elf64_archive_write_ar_hdr): Likewise.
	(bfd_elf64_archive_openr_next_archived_file): Likewise.
	(bfd_elf64_archive_get_elt_at_index): Likewise.
	(bfd_elf64_archive_generic_stat_arch_elt): Likewise.
	(bfd_elf64_archive_update_armap_timestamp): Likewise.
	* elf64-s390.c (bfd_elf64_archive_functions): Removed.
	(bfd_elf64_archive_slurp_armap): Likewise.
	(bfd_elf64_archive_write_armap): Likewise.
	(bfd_elf64_archive_slurp_extended_name_table): Likewise.
	(bfd_elf64_archive_construct_extended_name_table): Likewise.
	(bfd_elf64_archive_truncate_arname): Likewise.
	(bfd_elf64_archive_read_ar_hdr): Likewise.
	(bfd_elf64_archive_write_ar_hdr): Likewise.
	(bfd_elf64_archive_openr_next_archived_file): Likewise.
	(bfd_elf64_archive_get_elt_at_index): Likewise.
	(bfd_elf64_archive_generic_stat_arch_elt): Likewise.
	(bfd_elf64_archive_update_armap_timestamp): Likewise.
	* elfxx-target.h (TARGET_BIG_SYM): Use _bfd_archive_64_bit on
	BFD_JUMP_TABLE_ARCHIVE if USE_64_BIT_ARCHIVE is defined and
	bfd_elfNN_archive_functions isn't defined.
	(TARGET_LITTLE_SYM): Likewise.
	* libbfd-in.h (_bfd_archive_64_bit_slurp_armap): New prototype.
	(_bfd_archive_64_bit_write_armap): Likewise.
	(_bfd_archive_64_bit_slurp_extended_name_table): New macro.
	(_bfd_archive_64_bit_construct_extended_name_table): Likewise.
	(_bfd_archive_64_bit_truncate_arname): Likewise.
	(_bfd_archive_64_bit_read_ar_hdr): Likewise.
	(_bfd_archive_64_bit_write_ar_hdr): Likewise.
	(_bfd_archive_64_bit_openr_next_archived_file): Likewise.
	(_bfd_archive_64_bit_get_elt_at_index): Likewise.
	(_bfd_archive_64_bit_generic_stat_arch_elt): Likewise.
	(_bfd_archive_64_bit_update_armap_timestamp): Likewise.
	* libbfd.h: Regenerated.
	* plugin.c (plugin_vec): Use _bfd_archive_64_bit on
	BFD_JUMP_TABLE_ARCHIVE if USE_64_BIT_ARCHIVE is defined.

binutils/

	PR binutils/14625
	* NEWS: Mention --enable-64-bit-archive.

bfd/plugin.c

@@ -597,7 +597,11 @@ const bfd_target plugin_vec =
   BFD_JUMP_TABLE_GENERIC (bfd_plugin),
   BFD_JUMP_TABLE_COPY (bfd_plugin),
   BFD_JUMP_TABLE_CORE (bfd_plugin),
+#ifdef USE_64_BIT_ARCHIVE
+  BFD_JUMP_TABLE_ARCHIVE (_bfd_archive_64_bit),
+#else
   BFD_JUMP_TABLE_ARCHIVE (_bfd_archive_coff),
+#endif
   BFD_JUMP_TABLE_SYMBOLS (bfd_plugin),
   BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
   BFD_JUMP_TABLE_WRITE (bfd_plugin),