Request a pthreads API for assigning names to individual threads.

pthread_setname_np / pthread_getname_np
Request a pthreads API for assigning names to individual threads. The interface can be non-portable. There is no known API for this currently implemented in AIX 7.1 thru TL3.

Requirements:
- Ability for a thread to set a string as its "name" via the pthread interface, i.e. pthread_setname_np. No specifications are asserted about uniqueness or string length; this is up to the implementors. No specifications are asserted about an external process being able to set the name of a thread.
- Ability to query that name via the pthread interface, i.e. pthread_getname_np. No specifications are asserted with respect to "no name set" or null (zero-length) name.
- Ability to query a thread's name from an external process. The method is not specified. (Might involve pthread_getname_np, pthread_getthrds_np, or some other API.)
- The thread names would be viewable in dbx. As a wish list item, the name would be viewable in gdb, Rational tools and kdb as well.
- An option to 'ps' for thread-display modes (-m or -o THREAD) to list these assigned names.

This enhancement would bring AIX in line with other platforms that have this facility, including:
- System i https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_71/apis/pthread_setname_np.htm
- Linux http://man7.org/linux/man-pages/man3/pthread_setname_np.3.html
- Solaris https://blogs.oracle.com/observatory/entry/named_threads