Add missing header to gpttool

Fixes a broken build from: https://android-git.corp.google.com/g/92563

Change-Id: I4d9a2eecde2a17aef0a35952c32483ec4af2b483

Author: rich cannings

gpttool/gpttool.c

@@ -25,6 +25,8 @@
 
 #include <linux/fs.h>
 
+#include <sys/stat.h>
+
 typedef unsigned char u8;
 typedef unsigned short u16;
 typedef unsigned int u32;