* runtime_sigprof.cpp (freqency): Change to 100.
(max_idle_times): Max idle times that can be endured.
(pipes): New global. Use to store pipes generated by pipe api.
These pipes are to pass the pointer of a record.
(struct ThreadInfo): New field idle_times_, used to record how many times
we have met idle.
(ThreadInfo::Clear): Clear the thread info in the current thread.
(delete_thread_info): Use ThreadInfo::Clear.
(myhandler): Clear the thread info after max_idle_times.
(Initializer::Initializer): New the pipes. New the writer thread.
(Initializer::~Initializer): Close the pipes.
(struct Record): New struct. To record the fields thread info and
trace struct.
(record_this): Pass pointer to struct Record instead of block writing.
(writer_thread): Read the pointer and write.