libg/eglibc: add updated eglibc 2.15

Includes a patch to remove __builtin_expect test:

In eglibc-2.15, the build breaks in configure while testing
for the existance of __builtin_expect. It fails with newer
versions of gcc.

This patch is a modification of an upstream change in glibc
mainline (to be 2.16) to fix the following error:

[CFG ] checking for __builtin_expect... no
[ERROR] configure: error: support for __builtin_expect needed

http://sourceware.org/git/?p=glibc.git;a=commit;h=3857022a761ea7251f8e5c0e45d382ebc3e34cf9

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
[yann.morin.1998@free.fr: coalesce both patches into a single changeset]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 # Options specific to crosstool-NG acting as a backend

 config IS_A_BACKEND

     string

     option env="CT_IS_A_BACKEND"

 config BACKEND

     bool

     default y if IS_A_BACKEND = "y" || IS_A_BACKEND = "Y"

 config BACKEND_ARCH

     string

     option env="CT_BACKEND_ARCH"

 config BACKEND_KERNEL

     string

     option env="CT_BACKEND_KERNEL"

 config BACKEND_LIBC

     string

     option env="CT_BACKEND_LIBC"