Update to kernel headers v4.7.2.

Modify the kernel header update script to rename C++ keyword
struct members to something else. This fixes problems when including
these kernel files in C++ code.

Also, make a manual change to linux/fib_rules.h and comment out the
value FRA_PAD since it conflicts with a special android kernel value
FRA_UID_START that has not been upstreamed yet.

Test: Built aosp_angler, aosp_x86_64, aosp_mips (bionic only)
Test: Booted on angler and ran bionic unit tests
Test: Built these changes in internal master

Change-Id: Ia22b7e3ca409404696dba76311f49157f4a9ceed
diff --git a/libc/kernel/uapi/asm-x86/asm/sigcontext.h b/libc/kernel/uapi/asm-x86/asm/sigcontext.h
index c9dbc50..da14068 100644
--- a/libc/kernel/uapi/asm-x86/asm/sigcontext.h
+++ b/libc/kernel/uapi/asm-x86/asm/sigcontext.h
@@ -182,7 +182,7 @@
   __u16 gs;
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
   __u16 fs;
-  __u16 __pad0;
+  __u16 ss;
   __u64 err;
   __u64 trapno;
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
@@ -254,20 +254,23 @@
   __u16 cs;
   __u16 gs;
   __u16 fs;
-  __u16 __pad0;
+  union {
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
+    __u16 ss;
+    __u16 __pad0;
+  };
   __u64 err;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
   __u64 trapno;
   __u64 oldmask;
   __u64 cr2;
-/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
   struct _fpstate __user * fpstate;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #ifdef __ILP32__
   __u32 __fpstate_pad;
 #endif
-/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
   __u64 reserved1[8];
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 };
 #endif
 #endif
-/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */