tracing/filters: Defer pred allocation

init_preds() allocates about 5392 bytes of memory (on x86_32) for
a TRACE_EVENT. With my config, at system boot total memory occupied
is:

	5392 * (642 + 15) == 3459KB

642 == cat available_events | wc -l
15 == number of dirs in events/ftrace

That's quite a lot, so we'd better defer memory allocation util
it's needed, that's when filter is used.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <4A9B8EA5.6020700@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/syscalls.h

@@ -177,7 +177,6 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		event_enter_##sname.id = id;				\
 		set_syscall_enter_id(num, id);				\
 		INIT_LIST_HEAD(&event_enter_##sname.fields);		\
-		init_preds(&event_enter_##sname);			\
 		return 0;						\
 	}								\
 	TRACE_SYS_ENTER_PROFILE(sname);					\
@@ -214,7 +213,6 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		event_exit_##sname.id = id;				\
 		set_syscall_exit_id(num, id);				\
 		INIT_LIST_HEAD(&event_exit_##sname.fields);		\
-		init_preds(&event_exit_##sname);			\
 		return 0;						\
 	}								\
 	TRACE_SYS_EXIT_PROFILE(sname);					\