tracing: Change trace event sample to use strlcpy instead of strncpy

Strings should be copied with strlcpy instead of strncpy when they will
later be printed via %s. This guarantees that they terminate with a
NUL '\0' character and do not run pass the end of the allocated string.

This is only for sample code, but it should stil represent a good
role model.

Link: http://lkml.kernel.org/p/[email protected]

Signed-off-by: Zhao Hongjiang <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

samples/trace_events/trace-events-sample.h

@@ -87,7 +87,7 @@ TRACE_EVENT(foo_bar,
 	),
 
 	TP_fast_assign(
-		strncpy(__entry->foo, foo, 10);
+		strlcpy(__entry->foo, foo, 10);
 		__entry->bar	= bar;
 	),