* cygthread.cc (cygthread::stub): Properly establish _threadinfo environment.

* cygthread.cc (cygthread::stub): Properly establish _threadinfo environment.
(cygthread::stub2): New function.
(cygthread::simplestub): Ditto.
(cygthread::simplestub2): New function.
* cygthread.h (cygthread::stub2): Declare new function.
(cygthread::simplestub2): Ditto.
* cygtls.h (_threadinfo::call): Declare new function.
(_threadinfo::call2): Ditto.
* dcrt0.cc (dll_crt0_1): Accommodate new _threadinfo::init which doesn't return
pointer to tls.
(_dll_crt0): Remove obsolete DECLARE_TLS_STORAGE.
(dll_crt0): Ditto.
* exceptions.cc (_threadinfo::call): New function.
(_threadinfo::call2): Ditto.
(_threadinfo::init): Don't return pointer.
* thread.cc (pthread::thread_init_wrapper): Properly establish _threadinfo
environment.
(pthread::thread_init_wrapper2): New function.
* thread.h (pthread::thread_init_wrapper): Remove noreturn attribute
(pthread::thread_init_wrapper2): Declare new function.
* winbase.h: Remove obsolete code.