openpower: Move to glibc 2.23

setlocale is broken for glibc 2.22. Upstream has a patch in the 2.22
release branch (strcoll: Remove incorrect STRDIFF-based optimization
(Bug 18589)), but has not made any releases from this branch.

We can solve the problem and gain the other bugfixes, such as a fix for
CVE-2015-7547: getaddrinfo() stack-based buffer overflow.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/openpower/configs/firestone_defconfig b/openpower/configs/firestone_defconfig
index eb4eb30..5cf127f 100644
--- a/openpower/configs/firestone_defconfig
+++ b/openpower/configs/firestone_defconfig
@@ -6,7 +6,7 @@
 BR2_EXTRA_GCC_CONFIG_OPTIONS="--enable-targets=powerpc64-linux"
 BR2_TOOLCHAIN_BUILDROOT_CXX=y
 # BR2_TOOLCHAIN_BUILDROOT_LIBSTDCPP is not set
-BR2_GLIBC_VERSION_2_22=y
+BR2_GLIBC_VERSION_2_23=y
 
 BR2_OPENPOWER_CONFIG_NAME="firestone"
 BR2_OPENPOWER_XML_PACKAGE="firestone-xml"