Calling pjsua_create() after pjsua_destroy() fails

[bennylp]

Some application want to be able to call pjsua_create() after calling pjsua_destroy(). Currently this sequence fails because the error subsystem has already been registered and subsequent registration will be refused.

The solution perhaps is to clear the error subsystem once pj_shutdown() is called.

[bennylp]

Few things that should be cleared by pj_shutdown():

• pj/errno.c should provide a function to clear all currently registered error handlers (e.g. pj_errno_clear_handlers(), which set err_msg_hnd_cnt to zero).
• the exception_cleanup() function in pj/except.c should also clear exception_id_names array (if PJ_HAS_EXCEPTION_NAMES is defined, of course).

[bennylp]

Replying to bennylp:

.. and pj_errno_clear_handlers() should be called by pj_shutdown(), of course.

[bennylp]

Fixed in r839