Add attribute printf to _bfd_error_handler

Add attribute printf to _bfd_error_handler

and fix a few stray errors.

	* elf-attrs.c (_bfd_elf_parse_attributes): Correct _bfd_error_handler
	arguments.
	* elfxx-mips.c (_bfd_mips_elf_final_link): Likewise.
	* elfnn-riscv.c (_bfd_riscv_relax_align): Likewise.
	(_bfd_riscv_relax_pc): Likewise and fix typos.
	* libbfd-in.h (_bfd_error_handler): Add attribute printf.
	* libbfd.h: Regenerate.