tracing/events: add export symbols for trace events in modules

Impact: let modules add trace events

The trace event code requires some functions to be exported to allow
modules to use TRACE_EVENT. This patch adds EXPORT_SYMBOL_GPL to the
necessary functions.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c0047fc..2d69b26 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -176,6 +176,7 @@
 {
 	return filter_check_discard(call, rec, global_trace.buffer, event);
 }
+EXPORT_SYMBOL_GPL(filter_current_check_discard);
 
 cycle_t ftrace_now(int cpu)
 {
@@ -886,6 +887,7 @@
 	return trace_buffer_lock_reserve(&global_trace,
 					 type, len, flags, pc);
 }
+EXPORT_SYMBOL(trace_current_buffer_lock_reserve);
 
 void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
 					unsigned long flags, int pc)
@@ -903,6 +905,7 @@
 {
 	ring_buffer_discard_commit(global_trace.buffer, event);
 }
+EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
 
 void
 trace_function(struct trace_array *tr,