crossgcc: Resolve pointer and integer comparison in GCC

GCC version 7 is being a bit picky about pointer and integer comparison
by default, which triggers a crossgcc build error.

This backports a patch from upstream GCC to fix the issue.

Change-Id: I8b1e806c10604c0df080ac5edc667bf1141e2c17
Signed-off-by: Paul Kocialkowki <contact@paulk.fr>
Reviewed-on: https://review.coreboot.org/20103
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/crossgcc/patches/gcc-6.3.0_pointer_integer.patch

@@ -0,0 +1,27 @@
+From 8db2cf6353c13f2a84cbe49b689654897906c499 Mon Sep 17 00:00:00 2001
+From: kyukhin <kyukhin@138bc75d-0d04-0410-961f-82ee72b054a4>
+Date: Sat, 3 Sep 2016 10:57:05 +0000
+Subject: [PATCH] gcc/ 	* ubsan.c (ubsan_use_new_style_p): Fix check for empty
+ string.
+
+git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@239971 138bc75d-0d04-0410-961f-82ee72b054a4
+---
+ gcc/ubsan.c   | 2 +-
+ 2 files changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/gcc/ubsan.c b/gcc/ubsan.c
+index 5cbc98dbabb..d3bd8e3393d 100644
+--- a/gcc/ubsan.c
++++ b/gcc/ubsan.c
+@@ -1469,7 +1469,7 @@ ubsan_use_new_style_p (location_t loc)
+ 
+   expanded_location xloc = expand_location (loc);
+   if (xloc.file == NULL || strncmp (xloc.file, "\1", 2) == 0
+-      || xloc.file == '\0' || xloc.file[0] == '\xff'
++      || xloc.file[0] == '\0' || xloc.file[0] == '\xff'
+       || xloc.file[1] == '\xff')
+     return false;
+ 
+-- 
+2.13.0
+