grub: Fix build with gcc-6

Backport patch which silences following

'../../grub-2.00/grub-core/'`gfxmenu/model.c
../../grub-2.00/grub-core/gettext/gettext.c:37:36: error: storage size of 'main_context' isn't known
 static struct grub_gettext_context main_context, secondary_context;
                                    ^~~~~~~~~~~~
make[3]: *** [gettext/gettext_module-gettext.o] Error 1

(From OE-Core rev: 4efac9861ab59d696bdc81ea59497febfa2d0dc8)

(From OE-Core rev: c1ad29a96dc38da87290b024c8b5a502baeea5e9)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-bsp/grub/files/0001-grub-core-gettext-gettext.c-main_context-secondary_c.patch

@@ -0,0 +1,39 @@
+From f30c692c1f9ef0e93bee2b408a24baa017f1ca9d Mon Sep 17 00:00:00 2001
+From: Vladimir Serbinenko <phcoder@gmail.com>
+Date: Thu, 7 Nov 2013 01:01:47 +0100
+Subject: [PATCH] 	* grub-core/gettext/gettext.c (main_context),
+ (secondary_context): 	Define after defining type and not before.
+
+---
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+Upstream-Status: Backport
+
+ ChangeLog                   | 5 +++++
+ grub-core/gettext/gettext.c | 4 ++--
+ 2 files changed, 7 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/gettext/gettext.c b/grub-core/gettext/gettext.c
+index df73570..4880cef 100644
+--- a/grub-core/gettext/gettext.c
++++ b/grub-core/gettext/gettext.c
+@@ -34,8 +34,6 @@ GRUB_MOD_LICENSE ("GPLv3+");
+    http://www.gnu.org/software/autoconf/manual/gettext/MO-Files.html .
+ */
+ 
+-static struct grub_gettext_context main_context, secondary_context;
+-
+ static const char *(*grub_gettext_original) (const char *s);
+ 
+ struct grub_gettext_msg
+@@ -69,6 +67,8 @@ struct grub_gettext_context
+   struct grub_gettext_msg *grub_gettext_msg_list;
+ };
+ 
++static struct grub_gettext_context main_context, secondary_context;
++
+ #define MO_MAGIC_NUMBER 		0x950412de
+ 
+ static grub_err_t
+-- 
+1.9.1
+

meta/recipes-bsp/grub/grub2.inc

@@ -30,6 +30,7 @@ SRC_URI = "ftp://ftp.gnu.org/gnu/grub/grub-${PV}.tar.gz \
            file://0001-Fix-CVE-2015-8370-Grub2-user-pass-vulnerability.patch \
            file://0001-Remove-direct-_llseek-code-and-require-long-filesyst.patch \
            file://fix-texinfo.patch \
+           file://0001-grub-core-gettext-gettext.c-main_context-secondary_c.patch \
             "
 
 DEPENDS = "flex-native bison-native"