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

--- glibc-2_9.orig/nptl/init.c	2007-10-15 22:25:25.000000000 +0200

+++ glibc-2_9/nptl/init.c	2010-08-18 10:46:06.109098646 +0200

@@ -236,7 +236,7 @@

 /* This can be set by the debugger before initialization is complete.  */

-static bool __nptl_initial_report_events;

+static bool __nptl_initial_report_events __attribute_used__;

 void

 __pthread_initialize_minimal_internal (void)