binutils: add support for arm-*-darwin and aarch64-*-darwin.

binutils: add support for arm-*-darwin and aarch64-*-darwin.

Currently only in bfd and binutils.

ChangeLog/
	* configure.ac: Add aarch64-*-darwin* and arm-*-darwin*.
	* configure: Regenerate.

bfd/ChangeLog/
	* targets.c (aarch64_mach_o_vec, arm_mach_o_vec): Declare.
	(_bfd_target_vector): Add new vectors.
	* reloc.c (BFD_RELOC_MACH_O_SUBTRACTOR32)
	(BFD_RELOC_MACH_O_SUBTRACTOR64, BFD_RELOC_MACH_O_ARM64_ADDEND)
	(BFD_RELOC_MACH_O_ARM64_GOT_LOAD_PAGE21)
	(BFD_RELOC_MACH_O_ARM64_GOT_LOAD_PAGEOFF12)
	(BFD_RELOC_MACH_O_ARM64_POINTER_TO_GOT): New relocations.
	(BFD_RELOC_MACH_O_X86_64_SUBTRACTOR32)
	(BFD_RELOC_MACH_O_X86_64_SUBTRACTOR64): Remove.
	* mach-o-x86-64.c (bfd_mach_o_x86_64_swap_reloc_out): Change
	name of subtractor relocations.
	* config.bfd: Handle aarch64-*-darwin*, arm-*-darwin*.
	* Makefile.am (BFD32_BACKENDS): Add mach-o-arm.lo.
	(BFD32_BACKENDS_CFILES): Add mach-o-arm.c.
	(BFD64_BACKENDS): Add mach-o-aarch64.lo.
	(BFD64_BACKENDS_CFILES): Add mach-o-aarch64.c.
	* configure.ac: Handle aarch64_mach_o_vec and arm_mach_o_vec.
	* mach-o-aarch64.c: New file.
	* mach-o-arm.c: New file.
	* Makefile.in: Regenerate.
	* bfd-in2.h: Regenerate.
	* configure: Regenerate.
	* libbfd.h: Regenerate.