boost file lock output

$ ./test_boost_file_lock &
[1] 13304
Process with PID: 13304 has lock on file: foo
$ ./test_boost_file_lock &
[2] 13306
Process with PID: 13306 has lock on file: foo
13306 still holding on to lock on foo
13304 still holding on to lock on foo
13306 still holding on to lock on foo
13304 still holding on to lock on foo
13306 still holding on to lock on foo
$ fg
./test_boost_file_lock
Caught signal: 2
Exiting now
$ fg
./test_boost_file_lock
Caught signal: 2
Exiting now
$