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

 Enable using a shell other than bash.

 Courtesy "Martin Guy" <martinwguy@yahoo.it>

 http://sourceware.org/ml/crossgcc/2008-08/msg00037.html

 --- binutils-2.18.orig/ld/genscripts.sh	2007-08-12 20:00:07.000000000 +0100

 +++ binutils-2.18/ld/genscripts.sh	2008-08-25 16:09:54.000000000 +0100

 @@ -398,9 +398,11 @@

      . $em_script

      em_script=$current_script

    }

 -  fragment()

 +  

 +  alias fragment='em_lineno=$LINENO; fragment_em'

 +  fragment_em()

    {

 -    local lineno=$[${BASH_LINENO[0]} + 1]

 +    local lineno=$[$em_lineno + 1]

      echo >> e${EMULATION_NAME}.c "#line $lineno \"$em_script\""

      cat >> e${EMULATION_NAME}.c

    }