Update to kernel headers v5.3.2.

Test: Builds and run unit tests on taimen/cuttlefish.
Change-Id: I6ebd8f179d159ac974555e8edca588083e8081b3
diff --git a/libc/kernel/uapi/linux/snmp.h b/libc/kernel/uapi/linux/snmp.h
index 2a48541..9f500ca 100644
--- a/libc/kernel/uapi/linux/snmp.h
+++ b/libc/kernel/uapi/linux/snmp.h
@@ -251,6 +251,7 @@
   LINUX_MIB_TCPZEROWINDOWDROP,
   LINUX_MIB_TCPRCVQDROP,
   LINUX_MIB_TCPWQUEUETOOBIG,
+  LINUX_MIB_TCPFASTOPENPASSIVEALTKEY,
   __LINUX_MIB_MAX
 };
 enum {