arc: Add new ARCv3 ISA to BFD.

The new Synopsys's ARCv3 ISA is capable to run either 64-bit or
32-bit ISA.  The new 32-bit ISA is not compatible with the old
Synopsys ARCv1/ARCv2 ISA, however, it retains a lot of common
concepts.  Thus, this patch is reusing the old ARC BFD backend and
adds the necessary bits for the new architecture in a similar way as
it is done for RISCV backend.

bfd/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>
	    Cupertino Miranda  <cupertinomiranda@gmail.com>

	* bfd/Makefile.am: Add ARC64 files.
	* bfd/Makefile.in: Regerate.
	* bfd/arc-got.h (TCB_SIZE): Depends on the target architecture.
	(GOT_ENTRY_SIZE): New define.
	(write_in_got): Likewise.
	(read_from_got): Likewise.
	(align_power): Likewise.
	(arc_got_entry_type_for_reloc): Use RELA_SIZE and GOT_ENTRY_SIZE.
	(arc_fill_got_info_for_reloc): Update formating.
	(relocate_fix_got_relocs_for_got_info): Likewise.
	(arc_static_sym_data): Deleted structure.
	(get_static_sym_data): Deleted function.
	(relocate_fix_got_relocs_for_got_info): Use symbol static data.
	(create_got_dynrelocs_for_single_entry): Update formating.
	(create_got_dynrelocs_for_got_info): Likewise.
	* bfd/arc-plt.c: New file.
	* bfd/arc-plt.def: Add ARC64 PLT entry.
	* bfd/arc-plt.h: Clean it up, move functionality to arc-plt.c file.
	* bfd/archures.c: Add ARC64 target.
	* bfd/config.bfd: Likewise.
	* bfd/configure.ac: Likewise.
	* bfd/bfd-in2.h: Regenerate.
	* bfd/configure: Likewise.
	* bfd/libbfd.h: Likewise.
	* bfd/cpu-arc.c: Clean it up.
	* bfd/cpu-arc64.c: New file.
	* bfd/elf32-arc.c: Renamed to elfnn-arc.c.
	* bfd/elfnn-arc.c: New file.
	* bfd/reloc.c: Add new ARC64 relocs.
	* bfd/targets.c: Add ARC64 target.

Signed-off-by: Claudiu Zissulescu <claziss@synopsys.com>