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

Index: ltrace-0.5.3/configure

===================================================================

--- ltrace-0.5.3/configure

+++ ltrace-0.5.3/configure

@@ -78,7 +78,10 @@ fi

 rm -f conftest.c a.out

 CFLAGS='-g -O2'

-LIBS='-lelf -lsupc++ -liberty '

+LIBS='-lelf'

+[ -n "$HAVE_LIBSUPC__" ] && LIBS="$LIBS -lsupc++"

+[ -n "$HAVE_LIBIBERTY" ] && LIBS="$LIBS -liberty"

+

 INSTALL='install -c'

 iquote='-iquote '

 iquoteend=''