* libguile/init.h:
* libguile/init.c (scm_i_init_guile): Change arg to this internal
function from SCM_STACKITEM* to void*. Actually it's a
struct GC_stack_base*.
* libguile/bdw-gc.h: Don't do pthread redirects, because we don't want
to affect applications' pthread_* bindings.
* libguile/pthread-threads.h (scm_i_pthread_create)
(scm_i_pthread_detach, scm_i_pthread_exit, scm_i_pthread_cancel)
(scm_i_pthread_sigmask): Do pthread redirects here, in this internal
header.
* libguile/threads.h: Remove declaration of internal
scm_i_with_guile_and_parent. Remove declaration of undefined
scm_threads_init_first_thread. Make declaration of internal
scm_threads_prehistory actually internal, and take a void* (actually a
struct GC_stack_base*).
* libguile/threads.c (GC_get_stack_base): Implement a shim if this
function is unavailable, and fold in the implementations of
get_thread_stack_base.
(GC_call_with_stack_base): Actually implement.
(guilify_self_1): Take a GC_stack_base* as an arg.
(scm_i_init_thread_for_guile): Likewise, and set up libgc for
registration of other threads.
(scm_init_guile): Use GC_get_stack_base instead of our own guesswork.
(with_guile_and_parent, scm_i_with_guile_and_parent): Rework to
trampoline through a GC_call_with_stack_base.
(scm_threads_prehistory): Pass the "base" arg on to guilify_self_1.
