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/linux/signal.h b/libc/kernel/uapi/linux/signal.h
index b8d7428..e9663ec 100644
--- a/libc/kernel/uapi/linux/signal.h
+++ b/libc/kernel/uapi/linux/signal.h
@@ -23,4 +23,7 @@
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define SS_ONSTACK 1
 #define SS_DISABLE 2
+#define SS_AUTODISARM (1U << 31)
+#define SS_FLAG_BITS SS_AUTODISARM
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif