(const): Move outside !HAVE_CONFIG_H conditional.

(const): Move outside !HAVE_CONFIG_H conditional.
(libintl.h): Include this if _LIBC.  Otherwise include gettext.h.
(wchar.h): Include, maybe.
(attribute_hidden): Define if not defind.
(__getopt_initialized): Use attribute_hidden.
(__libc_argc, __libc_argv): Renamed from original_argc, etc.
(__getopt_nonoption_flags, nonoption_flags_max_len, nonoption_flags_len):
Conditional on USE_NONOPTION_FLAGS.
(SWAP_FLAGS): New definitions.
(exchange): Test USE_NONOPTION_FLAGS.
(_getopt_initialize): Test USE_NONOPTION_FLAGS.
(_getopt_internal): Error if argc < 1.  New local var print_errors.
Improve test for ambiguous long option.
Add LIBIO support for error message output.
(NONOPTION_P): Test USE_NONOPTION_FLAGS.