On ppc64le with Ubuntu 18.04 and latest LibreOffice from master, the
build fails with the error below.

```
$ uname -m
ppc64le
$ git describe --dirty
libreoffice-6-1-branch-point-897-gd776263a
$ git log --oneline -1
d776263a (HEAD -> master, origin/master, origin/HEAD) uitest Calc-Statistics- Descriptive statistics
$ ./configure
[…]
$ make
[…]
checking build system type... ./config.guess: unable to guess system type

This script, last modified 2011-05-11, has failed to recognize
the operating system you are using. It is advised that you
download the most up to date version of the config scripts from

  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
and
  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

If the version you run (./config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <config-patches@gnu.org> in order to provide the needed
information to handle your system.

config.guess timestamp = 2011-05-11

uname -m = ppc64le
uname -r = 4.17.0-rc6+
uname -s = Linux
uname -v = #1 SMP Sun May 27 18:16:57 CEST 2018

/usr/bin/uname -p =
/bin/uname -X     =

hostinfo               =
/bin/universe          =
/usr/bin/arch -k       =
/bin/arch              =
/usr/bin/oslevel       =
/usr/convex/getsysinfo =

UNAME_MACHINE = ppc64le
UNAME_RELEASE = 4.17.0-rc6+
UNAME_SYSTEM  = Linux
UNAME_VERSION = #1 SMP Sun May 27 18:16:57 CEST 2018
configure: error: cannot guess build type; you must specify one
/dev/shm/libreoffice-core/external/libatomic_ops/ExternalProject_libatomic_ops.mk:19: recipe for target '/dev/shm/libreoffice-core/workdir/ExternalProject/libatomic_ops/build' failed
make[1]: *** [/dev/shm/libreoffice-core/workdir/ExternalProject/libatomic_ops/build] Error 1
make[1]: *** Waiting for unfinished jobs....
[…]
```

So, replace the library's config.sub and config.guess by the internal,
more up-to-date copies.

Change-Id: Ib92489943517a4204528f1039f6fba26363b33ee
Solution-by: David Tardon <dtardon@redhat.com>
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://gerrit.libreoffice.org/56054Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>