Assign names to threads

[gavv]

pthread allows to assign names to threads, which is very handy for debugging. For example, gdb will display this names.

We always create threads using core::Thread class. We can do the following:

• add new parameter const char * name to Thread constructor
• pass name everywhere where we create threads (preferably in form "roc_xxx", e.g. "roc_network_loop", "roc_control_loop")
• in Thread implementation, before calling run(), assign configured name to current thread

This SO answer gives an idea how to do it. Similar to Thread::get_tid, we should use ifdefs for different platforms.

[gavv]

Unassigning, so that someone could pick this up.

Here is the link to abandoned PR: #716