l10n: vi.po: Update Vietnamese translation

Signed-off-by: Trần Ngọc Quân <vnwildman@gmail.com>
xzgrep: Avoid passing both -q and -l to grep.

The behavior of grep -ql varies:
  - GNU grep behaves like grep -q.
  - OpenBSD grep behaves like grep -l.

POSIX doesn't make it 100 % clear what behavior is expected.
Anyway, using both -q and -l at the same time makes no sense
so both options simply should never be used at the same time.

Thanks to Christian Weisgerber.
Add support for AmigaOS/AROS to tuklib_physmem().

Thanks to Fredrik Wikstrom.
Update THANKS.
l10n: de.po: Fix typo: Schießen -> Schließen.

That's a funny one since "schießen" means to shoot :)

Signed-off-by: Andre Noll <maan@systemlinux.org>
l10n: de.po: Update German translation

Signed-off-by: Andre Noll <maan@systemlinux.org>
l10n: de.po: Change translator email address.

Although the old address is still working, the new one should
be preferred. So this commit changes all three places in de.po
accordingly.

Signed-off-by: Andre Noll <maan@tuebingen.mpg.de>
Translations: Update the Polish translation.

Thanks to Jakub Bogusz.
Translations: Update the Italian translation.

Thanks to Milo Casagrande.
Build: Prepare to support Automake's subdir-objects.

Due to a bug in Automake, subdir-objects won't be enabled
for now.

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=17354

Thanks to Daniel Richard G. for the original patches.
Update .gitignore files.
Update THANKS.
liblzma: Fix lzma_mt.preset in lzma_stream_encoder_mt_memusage().

It read the filter chain from a wrong variable. This is a similar
bug that was fixed in 9494fb6d0ff41c585326f00aa8f7fe58f8106a5e.
xzdiff: Create a temporary directory to hold a temporary file.

This avoids the possibility of "File name too long" when
creating a temp file when the input file name is very long.

This also means that other users on the system can no longer
see the input file names in /tmp (or whatever $TMPDIR is)
since the temporary directory will have a generic name. This
usually doesn't matter since on many systems one can see
the arguments given to all processes anyway.

The number X chars to mktemp where increased from 6 to 10.

Note that with some shells temp files or dirs won't be used at all.
xzdiff: Use mkdir if mktemp isn't available.
Build: Fix Autoconf warnings about escaped backquotes.

Thanks to Daniel Richard G. for pointing out that it's
good to sometimes run autoreconf -fi with -Wall.
Build: Replace obsolete AC_HELP_STRING with AS_HELP_STRING.
Build: Update m4/ax_pthread.m4 from Autoconf Archive.
liblzma: Verify the filter chain in threaded encoder initialization.

This way an invalid filter chain is detected at the Stream
encoder initialization instead of delaying it to the first
call to lzma_code() which triggers the initialization of
the actual filter encoder(s).
liblzma: Update lzma_stream_encoder_mt() API docs.