mach-o: use a per-target reloc canonicalize function.

mach-o: use a per-target reloc canonicalize function.

bfd/
	* mach-o.h (bfd_mach_o_swap_in_non_scattered_reloc)
	(bfd_mach_o_canonicalize_non_scattered_reloc)
	(bfd_mach_o_pre_canonicalize_one_reloc): Declare.
	(bfd_mach_o_backend_data): Rename field
	_bfd_mach_o_swap_reloc_in to _bfd_mach_o_canonicalize_one_reloc.
	* mach-o.c (bfd_mach_o_swap_in_non_scattered_reloc): Now public.
	(bfd_mach_o_canonicalize_non_scattered_reloc): Renames from
	bfd_mach_o_canonicalize_one_reloc.
	(bfd_mach_o_pre_canonicalize_one_reloc): New function.
	(bfd_mach_o_canonicalize_relocs): Adjust.
	(bfd_mach_o_canonicalize_relocs): Rename define from
	bfd_mach_o_swap_reloc_in.
	* mach-o-target.c (TARGET_NAME_BACKEND): Use
	bfd_mach_o_canonicalize_one_reloc instead of
	bfd_mach_o_swap_reloc_in.
	* mach-o-i386.c (bfd_mach_o_i386_canonicalize_one_reloc): Renames
	from bfd_mach_o_i386_swap_reloc_in and adjust.
	(bfd_mach_o_canonicalize_one_reloc): Renames from
	bfd_mach_o_i386_canonicalize_one_reloc.
	* mach-o-x86_64.c (bfd_mach_o_x86_64_canonicalize_one_reloc): Renames
	from bfd_mach_o_x86_64_swap_reloc_in and adjust.
	(bfd_mach_o_canonicalize_one_reloc): Renames from
	bfd_mach_o_x86_64_canonicalize_one_reloc.