efivar: fix build with gcc 7

Add upstream patch fixing a warning that breaks the build because of -Werror.

Fixes:
http://autobuild.buildroot.net/results/33a/33adc3ef139d6814aef4c92ae0bcc4c810ab0b86/
http://autobuild.buildroot.net/results/e7d/e7d80e823e13edc6698148244553bd90367bcd03/
http://autobuild.buildroot.net/results/3b6/3b61246f8b04a332d1c61732f0eb6e50ea8ca366/

Cc: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/efivar/0003-Remove-some-extra-const-that-gcc-complains-about.patch

@@ -0,0 +1,47 @@
+From 1c7c0f71c9d22efda4156881eb187b8c69d1cca7 Mon Sep 17 00:00:00 2001
+From: Peter Jones <pjones@redhat.com>
+Date: Mon, 6 Feb 2017 14:28:19 -0500
+Subject: [PATCH] Remove some extra "const" that gcc complains about.
+
+One of these days I'll get these right.
+
+Signed-off-by: Peter Jones <pjones@redhat.com>
+Signed-off-by: Baruch Siach <baruch@tkos.co.il>
+---
+Upstream commit 1c7c0f71c9d22e.
+
+ src/include/efivar/efiboot-loadopt.h | 4 ++--
+ src/loadopt.c                        | 2 +-
+ 2 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/src/include/efivar/efiboot-loadopt.h b/src/include/efivar/efiboot-loadopt.h
+index 07db5c4c53e3..efc29c69d47e 100644
+--- a/src/include/efivar/efiboot-loadopt.h
++++ b/src/include/efivar/efiboot-loadopt.h
+@@ -32,8 +32,8 @@ extern ssize_t efi_loadopt_create(uint8_t *buf, ssize_t size,
+ 
+ extern efidp efi_loadopt_path(efi_load_option *opt, ssize_t limit)
+ 	__attribute__((__nonnull__ (1)));
+-extern const unsigned char const * efi_loadopt_desc(efi_load_option *opt,
+-						    ssize_t limit)
++extern const unsigned char * efi_loadopt_desc(efi_load_option *opt,
++					      ssize_t limit)
+ 	__attribute__((__visibility__ ("default")))
+ 	__attribute__((__nonnull__ (1)));
+ extern uint32_t efi_loadopt_attrs(efi_load_option *opt)
+diff --git a/src/loadopt.c b/src/loadopt.c
+index a63ca792d2dc..ce889867fd29 100644
+--- a/src/loadopt.c
++++ b/src/loadopt.c
+@@ -357,7 +357,7 @@ teardown(void)
+ 
+ __attribute__((__nonnull__ (1)))
+ __attribute__((__visibility__ ("default")))
+-const unsigned char const *
++const unsigned char *
+ efi_loadopt_desc(efi_load_option *opt, ssize_t limit)
+ {
+ 	if (last_desc) {
+-- 
+2.13.2
+