deps: Add modified xz-5.6.2

Deviations from upstream xz-5.6.2 release are in the CMake
infrastructure, to try and make the library more consumable as a
vendored dependency.

src/dependencies/xz-5.6.2/lib/getopt-core.h

@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+/* Declarations for getopt (basic, portable features only).
+   Copyright (C) 1989-2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library and is also part of gnulib.
+   Patches to this file should be submitted to both projects.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_CORE_H
+#define _GETOPT_CORE_H 1
+
+/* This header should not be used directly; include getopt.h or
+   unistd.h instead.  Unlike most bits headers, it does not have
+   a protective #error, because the guard macro for getopt.h in
+   gnulib is not fixed.  */
+
+__BEGIN_DECLS
+
+/* For communication from 'getopt' to the caller.
+   When 'getopt' finds an option that takes an argument,
+   the argument value is returned here.
+   Also, when 'ordering' is RETURN_IN_ORDER,
+   each non-option ARGV-element is returned here.  */
+
+extern char *optarg;
+
+/* Index in ARGV of the next element to be scanned.
+   This is used for communication to and from the caller
+   and for communication between successive calls to 'getopt'.
+
+   On entry to 'getopt', zero means this is the first call; initialize.
+
+   When 'getopt' returns -1, this is the index of the first of the
+   non-option elements that the caller should itself scan.
+
+   Otherwise, 'optind' communicates from one call to the next
+   how much of ARGV has been scanned so far.  */
+
+extern int optind;
+
+/* Callers store zero here to inhibit the error message 'getopt' prints
+   for unrecognized options.  */
+
+extern int opterr;
+
+/* Set to an option character which was unrecognized.  */
+
+extern int optopt;
+
+/* Get definitions and prototypes for functions to process the
+   arguments in ARGV (ARGC of them, minus the program name) for
+   options given in OPTS.
+
+   Return the option character from OPTS just read.  Return -1 when
+   there are no more options.  For unrecognized options, or options
+   missing arguments, 'optopt' is set to the option letter, and '?' is
+   returned.
+
+   The OPTS string is a list of characters which are recognized option
+   letters, optionally followed by colons, specifying that that letter
+   takes an argument, to be placed in 'optarg'.
+
+   If a letter in OPTS is followed by two colons, its argument is
+   optional.  This behavior is specific to the GNU 'getopt'.
+
+   The argument '--' causes premature termination of argument
+   scanning, explicitly telling 'getopt' that there are no more
+   options.
+
+   If OPTS begins with '-', then non-option arguments are treated as
+   arguments to the option '\1'.  This behavior is specific to the GNU
+   'getopt'.  If OPTS begins with '+', or POSIXLY_CORRECT is set in
+   the environment, then do not permute arguments.
+
+   For standards compliance, the 'argv' argument has the type
+   char *const *, but this is inaccurate; if argument permutation is
+   enabled, the argv array (not the strings it points to) must be
+   writable.  */
+
+extern int getopt (int ___argc, char *const *___argv, const char *__shortopts)
+       __THROW _GL_ARG_NONNULL ((2, 3));
+
+__END_DECLS
+
+#endif /* _GETOPT_CORE_H */