[source] kexec-tools: fix compile error

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/364ec6e0e0e651cbc5e6192d23e48ba86a5547a0

commit 364ec6e0e0e651cbc5e6192d23e48ba86a5547a0
Author: Gilles Mazoyer <mazoyer at gmazoyer-debian.ksl.fr>
AuthorDate: Fri Nov 18 13:22:27 2016 +0100

    kexec-tools: fix compile error
    
    When compiling file vmcore-dmesg.c, several errors "unknown type name 'loff_t'"
    
    Signed-off-by: Gilles Mazoyer <mazoyer.gilles at omega.ovh>
---
 .../patches/110-fix-vmcore-dmsg-compilation-error.patch       | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/package/boot/kexec-tools/patches/110-fix-vmcore-dmsg-compilation-error.patch b/package/boot/kexec-tools/patches/110-fix-vmcore-dmsg-compilation-error.patch
new file mode 100644
index 0000000..0cf2d3e
--- /dev/null
+++ b/package/boot/kexec-tools/patches/110-fix-vmcore-dmsg-compilation-error.patch
@@ -0,0 +1,11 @@
+--- a/vmcore-dmesg/vmcore-dmesg.c
++++ b/vmcore-dmesg/vmcore-dmesg.c
+@@ -1,6 +1,8 @@
+ #define _XOPEN_SOURCE 600
+ #define _LARGEFILE_SOURCE 1
+ #define _FILE_OFFSET_BITS 64
++#define _GNU_SOURCE
++
+ #include <endian.h>
+ #include <byteswap.h>
+ #include <stdio.h>