pr2_etherCAT diagnostics depends on ethercat_hardware object that can go out of scope while it is running.

[ahendrix]

Possible solutions:

• pthread_join at end of controlLoop where diagnostics thread is started.
• create ethercat_hardware object in main thread and pass pointer to control and diagnostic threads.

Migrated from: https://code.ros.org/trac/wg-ros-pkg/ticket/3474