df: improve mount point selection with inaccurate mount list

v8.23 has a test failure on Fedora rawhide build servers
in tests/df/skip-duplicate.sh.  This was due to no '/'
entry being output by df.  That was due to an inaccurate
/proc/mounts on the build environment as stat(/mnt/point)
identified all these /proc/mounts entries as having the
same device id:

  /                    rootfs
  /                    /dev/md1
  /dev                 devtmpfs
  /run                 tmpfs
  /boot                /dev/md0
  /proc/filesystems    /dev/md1

Since the device name on the right changes for a given id,
that causes the entries to be continually replaced, thus
resulting in no '/' entry.  I'm guessing this is due to
the mock environment bind mounting unneeded or sensitive
items to a dummy file on the host / (/dev/md1) though
have not looked into those details.

So rather than relying on an accurate /proc/mounts,
the attached patch takes a more conservative replacement
approach and only swaps a new device entry when the
mount point matches.  That should handle all practical
cases while also avoiding this situation.

* src/df.c (filter_mount_list): Only replace entries with
different device names when the mount point also matches.
doc: clarify that duplicate NFS mounts are skipped by df

* doc/coreutils.texi (df invocation): Add a sentence that eliding
duplicate entries for the same file system is not limited to bind
mounts, but also happens for remote file systems like NFS.
maint: refactor ls QUOTING_STYLE env var handling

* src/ls.c (main): As per the FIXME comment, move the
QUOTING_STYLE handling to a separate function.
maint: avoid int64_t and similar types unless they're needed

C11 doesn't require them, even POSIX doesn't strictly require the
64-bit versions, and it makes the code a bit clearer if they're
used only when needed.
* src/copy.c (write_zeros, extent_copy):
* src/extent-scan.h (struct extent_info.ext_length):
Use off_t, not uint64_t, for a value derived from a file offset.
* src/extent-scan.h (struct extent_info.ext_flags)
Prefer plain unsigned int to uint32_t where either will do.
(struct extent_scan.ei_count):
Use size_t, not uint32_t, for a value bounded by SIZE_MAX.
* src/factor.c (MAGIC64, MAGIC63, MAGIC65):
Remove unnecessary casts to uint64_t.
maint: ensure fiemap extents flags are compared correctly

* src/extent-scan.c (extent_scan_read): Following on from the flags size
adjustment in commit v8.23-13-g1505b37, verify that the internal
representation of the flags is never truncated which could happen in the
unlikely case on 32 bit if the kernel flags ever expanded to 64 bits
which is theoretically possible given the reserved space.
doc: spell "indeterminate" correctly

* doc/coreutils.texi (timeout invocation): Fix misspelling.
Reported by Yureruchihirosan via OKANO Takayoshi in:
http://bugs.gnu.org/18394
doc: fix typos

* doc/coreutils.texi: Fix normal typos:
s/pseudorandom/pseudo-random/;
s/behaviour/behavior/;
s/linux-based/Linux-based/;
s/nonnegative/non-negative/.
Fix IEC's long name: s/Electronical/Electrotechnical/.
Wrap 'getopt' into the @code{} macro.
Fix a grammatical error (from myself): s/splitted/split/.
doc: mention which commands are optional

* doc/coreutils.texi (coreutils invocation, df invocation)
(stty invocation, whoami invocation, nproc invocation)
(arch invocation, hostname invocation, hostid invocation)
(uptime invocation, chroot invocation, nice invocation)
(stdbuf invocation): Document that the command is installed
optionally.
doc: rename "coreutils invocation" to "Multi-call invocation"

This supports longstanding shell commands like
'info coreutils "touch invocation"'.
Problem reported by Vincent Lefevre via Bob Proulx in:
http://bugs.gnu.org/18428
* doc/coreutils.texi (Multi-call invocation):
Rename from "coreutils invocation".
maint: prefer 'return status;' to 'exit (status);' in 'main'

* build-aux/gen-single-binary.sh: Don't use ATTRIBUTE_NORETURN
for main functions.
* src/base64.c, src/basename.c, src/cat.c, src/chcon.c, src/chgrp.c:
* src/chmod.c, src/chown.c, src/chroot.c, src/cksum.c, src/comm.c:
* src/cp.c, src/csplit.c, src/cut.c, src/date.c, src/dd.c, src/df.c:
* src/dircolors.c, src/dirname.c, src/du.c, src/echo.c, src/env.c:
* src/expand.c, src/expr.c, src/factor.c, src/fmt.c, src/fold.c:
* src/getlimits.c, src/groups.c, src/head.c, src/hostid.c:
* src/hostname.c, src/id.c, src/install.c, src/join.c, src/kill.c:
* src/link.c, src/ln.c, src/logname.c, src/ls.c, src/make-prime-list.c:
* src/md5sum.c, src/mkdir.c, src/mkfifo.c, src/mknod.c, src/mktemp.c:
* src/mv.c, src/nice.c, src/nl.c, src/nohup.c, src/nproc.c:
* src/numfmt.c, src/od.c, src/paste.c, src/pathchk.c, src/pinky.c:
* src/pr.c, src/printenv.c, src/printf.c, src/ptx.c, src/pwd.c:
* src/readlink.c, src/realpath.c, src/rm.c, src/rmdir.c, src/runcon.c:
* src/seq.c, src/shred.c, src/shuf.c, src/sleep.c, src/sort.c:
* src/split.c, src/stat.c, src/stdbuf.c, src/stty.c, src/sum.c:
* src/sync.c, src/tac.c, src/tail.c, src/tee.c, src/timeout.c:
* src/touch.c, src/tr.c, src/true.c, src/truncate.c, src/tsort.c:
* src/tty.c, src/uname.c, src/unexpand.c, src/uniq.c, src/unlink.c:
* src/uptime.c, src/users.c, src/wc.c, src/who.c, src/whoami.c:
In 'main' functions, Prefer 'return status;' to 'exit (status);'.
* src/coreutils-arch.c (_single_binary_main_uname)
(_single_binary_main_arch):
* src/coreutils-dir.c, src/coreutils-vdir.c (_single_binary_main_ls)
(_single_binary_main_dir, _single_binary_main_vdir):
Omit ATTRIBUTE_NORETURN.  Return a value.
* src/coreutils.c (SINGLE_BINARY_PROGRAM): Omit ATTRIBUTE_NORETURN.
(launch_program): Now static.
* src/dd.c (finish_up): New function.
(quit, main): Use it.
* src/getlimits.c (main): Return a proper exit status.
* src/test.c (test_main_return): New macro.
(main): Use it.
* src/logname.c, src/nohup.c, src/whoami.c:
Use 'error' to simplify exit status in 'main' function.
* src/yes.c (main): Use 'return' rather than 'error' to exit,
so that GCC doesn't suggest ATTRIBUTE_NORETURN.
maint: avoid file-scope names of the form _[a-z]*

The C standard says this isn't portable, if you include
standard include files.
* build-aux/gen-single-binary.sh:
* src/coreutils-arch.c (single_binary_main_arch)
(single_binary_main_uname):
* src/coreutils-dir.c (single_binary_main_ls)
(_single_binary_main_dir):
* src/coreutils-vdir.c (single_binary_main_ls)
(_single_binary_main_vdir):
* src/coreutils.c (SINGLE_BINARY_PROGRAM):
Remove leading _ from single_binary prefix.
* src/numfmt.c (round_style): Rename from _round.  All uses changed.
(inval_style): Rename from _invalid.  All uses changed.
maint: fix syntax-check issues in recent commit

Avoid 2 new syntax-check failures introduced in commit v8.23-19-g8defcee

* cfg.mk (sc_some_programs_must_avoid_exit_failure): s/exit/return/.
* src/whoami.c (main): Reinstate translation marker for diagnostic.
build: avoid name transformations on libstdbuf

* src/local.mk (transform): Skip the transformation for libstdbuf
since that should not be subject to name clashes, and we need
to reference the name directly in LD_PRELOAD etc.
* configure.ac: Add a comment on the coupling of pkglibexec_PROGRAMS
to $(transform).
Issue reported at https://trac.macports.org/ticket/44922
Improved by Nick Bowler
build: adjust previous transformations on libstdbuf name

* src/local.mk (transform): commit v8.23-22-g6f9b018 discarded all
transformations on the libstdbuf.so name.  Be more conservative and
only exclude the $(program_transform_name) portion for libstdbuf.
maint: include libstdbuf.c in extraneous headers check

* cfg.mk (sc_system_h_headers): Don't exclude libstdbuf.c.
* src/libstdbuf.c: Remove headers already included in system.h.
doc: adjust reference to info nodes in man pages

old form: coreutils '$cmd invocation'
new form: '(coreutils) $cmd invocation'

The old form erroneously referenced the node for the 'coreutils'
multi-call program.  Now that problematic node name was renamed
in commit v8.23-18-g72e470b, but the newer less ambiguous form
also has the advantage of working with the pinfo viewer for example.
Full discussion at http://bugs.gnu.org/18428

* man/local.mk: Adjust man page references to texinfo nodes.
* src/system.h: Adjust --help references to texinfo nodes.
doc: reference online info pages directly from man pages

* src/system.h (emit_ancillary_info): Add a direct reference
to the corresponding online info documentation.  Corresponding
redirects were put in place on www.gnu.org to allow for concise links.
* help2man: Adjust to add the "online help" link (and subsequent
translation bugs link) to a "REPORTING BUGS" section.
Also add the concise links for further information in --help
to the "SEE ALSO" section, and dispense with the more verbose
default for that.
cat: allow copying empty files to themselves

Problem reported by Vincent Lefevre in: http://bugs.gnu.org/18449
* src/cat.c (main): Allow copying an empty file to itself.
* tests/misc/cat-self.sh: New test.
* tests/local.mk (all_tests): Add it.
tests: fix false du failure on newer XFS

On XFS, when creating the ~2G test file 'big' in a for-loop by
appending 20M each time, the file ends up using ~4G - visible in
'st_blocks'.  The unused space would be reclaimed later.
This feature is called "speculative preallocation" which aims at
avoiding fragmentation.
According to the XFS FAQ [1], there are two particular aspects of
XFS speculative preallocation that are triggering this:

  1. "Applications that repeatedly trigger preallocation and reclaim
     cycles [after file close] can cause fragmentation.
     Therefore, this pattern is detected and causes the preallocation
     to persist beyond the lifecycle of the file descriptor."

  2. "Preallocation sizes grow as files grow larger."

[1] http://xfs.org/index.php/XFS_FAQ

Avoid one of the above by only doing a single close (reclaim cycle).

* tests/du/2g.sh: Similar to the fix for a dd test (see commit
v8.22-65-g7c03fe2), avoid speculative preallocation by creating
the 'big' file in one go instead of appending to it in the loop.
Remove debugging statements as the output with 'set -x' is
sufficient nowadays.
doc: ensure the correct texinfo nodes are referenced in --help

* src/system.h (emit_ancillary_info): For commands that don't have
a 1:1 mapping with the texinfo node names, provide a mapping to
the correct node.
* doc/coreutils.texi: Add some extra cross references noticed while
checking this.
Fixes http://bugs.debian.org/762092