* objcopy.c (use_alt_mach_code): Change type to unsigned long.
(copy_object): If bfd_alt_mach_code fails emit a more helpful message
and if the target architecture is ELF use the alternative as replacement
value for the e_machine number.
(copy_main): Use strtoul to parse the number provided with the
--alt-mach-code switch.
* doc/binutils.texi (--alt-mach-code): Document that this switch can now
set the absolute e_machine value.