blame: avoid "diff -u0".

As Linus suggests, use "diff -u -U 0" instead.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

blame.c

@@ -92,7 +92,7 @@ static struct patch *get_patch(struct commit *commit, struct commit *other)
 		die("write failed: %s", strerror(errno));
 	close(fd);
 
-	sprintf(diff_cmd, "diff -u0 %s %s", tmp_path1, tmp_path2);
+	sprintf(diff_cmd, "diff -u -U 0 %s %s", tmp_path1, tmp_path2);
 	fin = popen(diff_cmd, "r");
 	if (!fin)
 		die("popen failed: %s", strerror(errno));