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

Original patch from http://www.nabble.com/arm-linux-compilation-failure-and-possible-fix-td19229074.html

diff -durN glibc-2.9.orig/ports/sysdeps/unix/sysv/linux/arm/sysdep.h glibc-2.9/ports/sysdeps/unix/sysv/linux/arm/sysdep.h

--- glibc-2.9.orig/ports/sysdeps/unix/sysv/linux/arm/sysdep.h 25 Nov 2008 16:37:26 -0000 1.33

+++ glibc-2.9/ports/sysdeps/unix/sysv/linux/arm/sysdep.h 27 Jan 2009 15:35:38 -0000

@@ -28,6 +28,8 @@

 /* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */

 #include <dl-sysdep.h>

+#include <tls.h>

+

 /* For Linux we can use the system call table in the header file

	/usr/include/asm/unistd.h

    of the kernel.  But these symbols do not follow the SYS_* syntax