build: fix an inverted test breaking dummy-man

* man/dummy-man: Fix argument count check,
allowing dummy-man to run (on systems without perl).
Fixes http://bugs.gnu.org/18531
build: fix argument count check in dummy-man again

* man/dummy-man: Fix argument count check, now only permitting
exactly 1 argument, the program name.
Reported by Andreas Schwab <schwab@linux-m68k.org>
build: pass program name to help2man after other options

* man/local.mk (.x.1): Move the program name argument down after
the last option argument when calling $(run_help2man).
While the other way would be accepted for the GNU help2man program,
it is not for the 'dummy-man' script (called as a fallback on
systems lacking perl).
The wrong order was introduced in commit v8.21-119-gb3578fc while
adding the --info-page option.
doc: fix use of "e.g." in stdbuf help message

"E.g." stands for latin "exempli gratia" which is typically read
as "for example".  "E.g." does not stand for the word "example".
As such, "for e.g." might be read as "for for example".

Fix this usage by simply replacing "e.g." with "example".
stty: only list supported options in --help and man pages

* src/stty.c (usage): Exclude unsupported options from --help,
which for example impacts the "dsusp" and "cdtrdsr" options on Linux.
Fixes http://bugs.gnu.org/18506
mv: use reflink=auto mode by default

On some filesystems (BTRFS), moving a file within the filesystem may
cross subvolume boundaries and we can use a lightweight reflink copy,
similar to what cp(1) can do, which is faster than a full file copy.
This is enabled by default because it's only an optimization for
the fall back copy and does not break user expectations or usability.

* src/mv.c (cp_option_init): Set the reflink mode to AUTO.
* NEWS: Mention the improvement.
test: check for Fedora 20 sort key bug

Problem reported by Göran Uddeborg in: http://bugs.gnu.org/18540
* tests/misc/sort.pl: New test 23.