* elfedit.c (input_elf_type): New.
(output_elf_type): Likewise.
(elf_type): Likewise.
(update_elf_header): Support updating ELF file type.
(command_line_switch): Add OPTION_INPUT_TYPE and
OPTION_OUTPUT_TYPE.
(options): Likewise.
(usage): Add --input-type and --output-type.
(main): Handle OPTION_INPUT_TYPE and OPTION_OUTPUT_TYPE. Check
one of --output-mach and --output-type must be specified.
* doc/binutils.texi: Document --input-type and --output-type
for elfedit.