kasan: update kasan_global for gcc 7

kasan_global struct is part of compiler/runtime ABI.  gcc revision
241983 has added a new field to kasan_global struct.  Update kernel
definition of kasan_global struct to include the new field.

Without this patch KASAN is broken with gcc 7.

Link: http://lkml.kernel.org/r/1479219743-28682-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: <stable@vger.kernel.org>	[4.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 432f5c9..928e5ca 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -263,7 +263,9 @@
 #endif
 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
 
-#if GCC_VERSION >= 50000
+#if GCC_VERSION >= 70000
+#define KASAN_ABI_VERSION 5
+#elif GCC_VERSION >= 50000
 #define KASAN_ABI_VERSION 4
 #elif GCC_VERSION >= 40902
 #define KASAN_ABI_VERSION 3