Fix lseek on mingw. * modules/lseek: New module. * m4/lseek.m4: New file. * lib/lseek.c: New file. * modules/lseek-tests: New file. * tests/test-lseek.c: New file. * tests/test-lseek.sh: New file. * MODULES.html.sh: Document lseek module. * modules/fflush (Depends-on): Add lseek, fseeko. * modules/fseeko (Depends-on): Likewise. * modules/ftello (Depends-on): Likewise. * m4/fseeko.m4 (gl_FUNC_FSEEKO): Replace fseek[o] if lseek is broken. * m4/ftello.m4 (gl_FUNC_FTELLO): Replace ftell[o] if lseek is broken. * m4/fflush.m4 (gl_REPLACE_FFLUSH): Trigger fseeko module. * lib/fseeko.c (rpl_fseeko): Quit early on non-seekable files. * lib/ftello.c (rpl_ftello): Likewise. * tests/test-fseeko.c (main): Test this. * tests/test-fseeko.sh: Likewise. * tests/test-ftello.c (main): Likewise. * tests/test-ftello.sh: Likewise. * lib/stdio_.h (fseek, ftell): Simplify, since missing fseeko now implies replacing fseek. * modules/stdio (Makefile.am): No longer need HAVE_FSEEKO, HAVE_FTELLO. * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Add lseek info. * modules/unistd (Makefile.am): Likewise. * lib/unistd_.h (lseek): Declare a replacement. * doc/functions/lseek.texi (lseek): Document this fix. * doc/functions/fseek.texi (fseek): Likewise. * doc/functions/ftell.texi (ftell): Likewise.

# fseeko.m4 serial 3
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_FSEEKO],
[
  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([gl_STDIN_LARGE_OFFSET])
  AC_CACHE_CHECK([for fseeko], [gl_cv_func_fseeko],
    [
      AC_TRY_LINK([#include <stdio.h>], [fseeko (stdin, 0, 0);],
	[gl_cv_func_fseeko=yes], [gl_cv_func_fseeko=no])
    ])
  if test $gl_cv_func_fseeko = no; then
    HAVE_FSEEKO=0
    gl_REPLACE_FSEEKO
  elif test $gl_cv_var_stdin_large_offset = no; then
    gl_REPLACE_FSEEKO
  fi
])

AC_DEFUN([gl_REPLACE_FSEEKO],
[
  AC_LIBOBJ([fseeko])
  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
  REPLACE_FSEEKO=1
])