unix: add constants for netlink/audit

Change-Id: Idaa02498b43360fa647d52423bc2f4c0cd5a9523
Reviewed-on: https://go-review.googlesource.com/c/sys/+/416754
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

unix/linux/types.go

@@ -79,6 +79,7 @@ struct termios2 {
 #endif
 #include <asm/ptrace.h>
 
+#include <linux/audit.h>
 #include <linux/blkpg.h>
 #include <linux/bpf.h>
 #include <linux/can.h>
@@ -5506,3 +5507,10 @@ const (
 	FR_ACT_UNREACHABLE     = C.FR_ACT_UNREACHABLE
 	FR_ACT_PROHIBIT        = C.FR_ACT_PROHIBIT
 )
+
+// generated by:
+// perl -nlE '/^\s*(AUDIT_NLGRP_\w+)/ && say "$1 = C.$1"' audit.h
+const (
+	AUDIT_NLGRP_NONE    = C.AUDIT_NLGRP_NONE
+	AUDIT_NLGRP_READLOG = C.AUDIT_NLGRP_READLOG
+)