arch/powerpc: add powerpc64le support

Technically, I don't forbid powerpcle support either, but I'm not sure that
there is any library/compiler support for that at the moment (though the hw
technically makes it possible).

powerpc64le needs glibc 2.19 and gcc 4.9. I haven't looked into the support
tools, but at least gdb 7.5 is too old (7.7.1 definitely has support).

Also make powerpc64 non-experimental. It's practically old at this point.

Signed-off-by: Cody P Schafer <dev@codyps.com>
[yann.morin.1998@free.fr: use ${target_endian_le} and ${target_bits_64}]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <64bfbbced9dd8f62e0d6.1399801945@gun>
Patchwork-Id: 347775

diff -ru ltrace-0.5.3.org/configure ltrace-0.5.3/configure

--- ltrace-0.5.3.org/configure	2011-08-21 18:55:15.000000000 +0200

+++ ltrace-0.5.3/configure	2011-08-21 18:54:46.000000000 +0200

@@ -15,8 +15,12 @@

 echo $PACKAGE_VERSION

 echo -n "checking HOST_OS... "

-HOST_OS=$( uname -s )

-if [ "$HOST_OS" = "Linux" ]

+if [ -z "$HOST_OS" ] ; then

+  HOST_OS=$( uname -s )

+else

+  echo -n "using preset: "

+fi

+if [ "$HOST_OS" = "Linux" -o "$HOST_OS" = "linux" ]

 then

   HOST_OS="linux-gnu"

 fi