Extend the thread storage API such that a custom initialization function can

be called for each thread specific object after they are allocated.  Note that
there was already the ability to define a custom cleanup function.  Also, if
the custom cleanup function is used, it *MUST* call free on the thread
specific object at the end.  There is no way to have this magically done that
I can think of because the cleanup function registered with the pthread
implementation will only call the function back with a pointer to the
thread specific object, not the parent ast_threadstorage object.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@45623 65c4cc65-6c06-0410-ace0-fbb531ad65f3