bfd_merge_private_bfd_data tidy

bfd_merge_private_bfd_data tidy

bfd_merge_private_bfd_data and _bfd_generic_verify_endian_match are
linker functions, so move them to linker.c.

bfd/
	* Makefile.am (LIBBFD_H_FILES): Update.
	* doc/Makefile.am (LIBBFD_H_DEP): Likewise.
	* cpu-sh.c (sh_merge_bfd_arch): Move to..
	* elf32-sh.c: ..here, and make static.
	* elf32-arc.c (arc_elf_merge_private_bfd_data): Delete extraneous
	error.
	* elf32-cris.c (cris_elf_merge_private_bfd_data): Don't call
	_bfd_generic_verify_endian_match.
	* elf32-microblaze.c (microblaze_elf_merge_private_bfd_data): Delete.
	(bfd_elf32_bfd_merge_private_bfd_data): Define as
	_bfd_generic_verify_endian_match.
	* elf32-mt.c (mt_elf_merge_private_bfd_data): Don't test
	boolean == FALSE.
	* elf32-xgate.c (_bfd_xgate_elf_merge_private_bfd_data): Delete.
	(bfd_elf32_bfd_merge_private_bfd_data): Don't define.
	* elf32-xgate.h (_bfd_xgate_elf_merge_private_bfd_data): Delete.
	* libbfd-in.h (_bfd_generic_verify_endian_match): Delete.
	* libbfd.c (_bfd_generic_verify_endian_match): Move to..
	* linker.c: ..here, and make internal.
	* bfd.c (bfd_merge_private_bfd_data): Move to..
	* linker.c: ..here.
	* Makefile.in: Regenerate.
	* doc/Makefile.in: Regenerate.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.
opcodes/
	* sh-opc.h (sh_merge_bfd_arch): Delete prototype.