* gc-mark.c (scm_mark_all): Do not rely on hooks to run the weak

* gc-mark.c (scm_mark_all): Do not rely on hooks to run the weak
hashtable and guardian machinery but call the relevant functions
directly.

* guardians.h, guardians.c, deprecated.h,
deprecated.c (scm_destroy_guardian_x, scm_guardian_greedy_p,
scm_guardian_destroyed_p, scm_guard, scm_get_one_zombie):
Deprecated and moved into deprecated.[ch].

* guardians.h, guardians.c: Mostly rewritten.
(scm_i_init_guardians_for_gc,
scm_i_identify_inaccessible_guardeds,
scm_i_mark_inaccessible_guardeds): New.

* weaks.h, weaks.c (SCM_I_WVECT_TYPE, SCM_I_SET_WVECT_TYPE): New.
(SCM_I_WVECT_N_ITEMS, SCM_I_SET_WVECT_N_ITEMS): New.
(SCM_WVECTF_NOSCAN, SCM_WVECT_NOSCAN_P): Removed.
(scm_weaks_prehistory): Removed.
(scm_i_init_weak_vectors_for_gc, scm_i_mark_weak_vector,
scm_i_mark_weak_vectors_non_weaks,
scm_i_remove_weaks_from_weak_vectors, scm_i_remove_weaks): New.
(scm_weak_vector_gc_init, scm_mark_weak_vector_spines,
scm_scan_weak_vectors): Removed.

* hashtab.h (scm_i_scan_weak_hashtables): New.
* hashtab.c (make_hash_table, scm_i_rehash): Do not use
SCM_WVECTF_NOSCAN.
(hashtable_print): Use SCM_HASHTABLE_N_ITEMS instead of
t->n_items.
(scan_weak_hashtables, scm_i_scan_weak_hashtables): Renamed former
to latter.  Do not scan the alists themselves, this is done by the
weak vector code now.  Just update the element count.

* vectors.h (SCM_I_WVECT_TYPE, SCM_I_WVECT_EXTRA): Renamed former
to latter.  The type is now only part of the cell word.
(SCM_I_SET_WVECT_TYPE, SCM_I_SET_WVECT_EXTRA): Likewise.

* init.c (scm_i_init_guile): Do not call scm_weaks_prehistory.