tracing/kprobes: Use bool for retprobe checker

Use bool instead of int for kretprobe checker.

Link: http://lkml.kernel.org/r/20130509054431.30398.38561.stgit@mhiramat-M0-7522

Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_kprobe.c

@@ -46,7 +46,7 @@ struct trace_probe {
 	(sizeof(struct probe_arg) * (n)))
 
 
-static __kprobes int trace_probe_is_return(struct trace_probe *tp)
+static __kprobes bool trace_probe_is_return(struct trace_probe *tp)
 {
 	return tp->rp.handler != NULL;
 }