Add support for new load commands added by Apple to the MACH-O file format.

Add support for new load commands added by Apple to the MACH-O file format.

bfd	* mach-o.h: Add new enums for BFD_MACH_O_PLATFORM_MACOS,
	BFD_MACH_O_PLATFORM_IOS, BFD_MACH_O_PLATFORM_TVOS,
	BFD_MACH_O_PLATFORM_WATCHOS, BFD_MACH_O_PLATFORM_BRIDGEOS,
	BFD_MACH_O_TOOL_CLANG, BFD_MACH_O_TOOL_SWIFT, BFD_MACH_O_TOOL_LD.
	(struct bfd_mach_o_note_command): New.
	(struct bfd_mach_o_build_version_tool): New.
	(struct bfd_mach_o_build_version_command): New.
	(bfd_mach_o_read_version_min): Don't split version into
	a few fields. Rename reserved to sdk.
	* mach-o.c (bfd_mach_o_read_version_min): Don't split version into a
	few fields. Rename reserved to sdk.
	(bfd_mach_o_read_command): Handle LC_VERSION_MIN_TVOS, LC_NOTE,
	LC_BUILD_VERSION.
	(bfd_mach_o_read_note): New.
	(bfd_mach_o_read_build_version): New.

	PR 23728
binutils* od-macho.c (printf_version): New.
	(dump_load_command): Use it to print version. Print sdk version. Print
	version info for watchOS and tvOS. Print LC_NOTE, LC_BUILD_VERSION.
	(dump_buld_version): New.
	(bfd_mach_o_platform_name): New
	(bfd_mach_o_tool_name): New

	* mach-o/external.h (mach_o_nversion_min_command_external): Rename
	reserved to sdk.
	(mach_o_note_command_external): New.
	(mach_o_build_version_command_external): New.
	* mach-o/loader.h (BFD_MACH_O_LC_VERSION_MIN_TVOS): Define.
	(BFD_MACH_O_LC_NOTE): Define.