[PATCH] get rid of loginuid races

Keeping loginuid in audit_context is racy and results in messier
code.  Taken to task_struct, out of the way of ->audit_context
changes.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/sched.h

@@ -1139,6 +1139,9 @@ struct task_struct {
 	void *security;
 #endif
 	struct audit_context *audit_context;
+#ifdef CONFIG_AUDITSYSCALL
+	uid_t loginuid;
+#endif
 	seccomp_t seccomp;
 
 /* Thread group tracking */