* gc.c (scm_igc): Don't call scm_i_thread_invalidate_freelists.

* gc.c (scm_igc): Don't call scm_i_thread_invalidate_freelists.

* gc.c (scm_gc_sweep): Call it here instead, which is a more
logical place.

* threads.c (create_thread): Remember root object until the handle
of the new thread is on all_threads list.

* root.c (scm_make_root): Moved copying of fluids until after
creation of root handle so that the fluids are GC protected.  Also
removed the critical section.