* gc.card.c (scm_gc_marked_p): Fixed compiler warning when
compiling with SCM_DEBUG==1 by moving definition behind prototype.
* gc.card.c (scm_dbg_t_list_cell, scm_dbg_t_double_cell,
scm_dbg_gc_marked_p, scm_dbg_gc_get_card, scm_dbg_gc_get_bvec,
scm_t_list_cell_struct, scm_t_list_cell, scm_t_double_cell,
scm_gc_marked_p, scm_gc_get_card, scm_gc_get_bvec): Fixed
functions such that they check if the object is a non-immediate.
Further, renamed identifiers to use the scm_dbg_ prefix and made
their inclusion into the lib dependent of the
SCM_DEBUG_DEBUGGER_SUPPORT compile time option.
SCM_EOL.
(scm_struct_prehistory): Move scm_free_structs to
scm_before_mark_c_hook.
* gc-card.c (sweep_card): Check that we haven't swept structs on
this card before. That can happen if scm_i_sweep_all_segments has
been called from some other place than scm_igc.
* gc-malloc.c (scm_gc_register_collectable_memory): use floats;
these won't ever wrap around with high memory usage.
* gc-malloc.c: add DEBUGINFO for mtrigger GCs.
* gc-malloc.c (scm_calloc): try to use calloc() before calling
scm_realloc().
* gc-segment.c (scm_i_initialize_heap_segment_data): remove card
init loop; handle this from scm_init_card_freelist()
* gc-card.c (scm_init_card_freelist): init bit vector here.
* gc-card.c ("sweep_card"): set scm_gc_running while sweeping.
* gc.c (scm_i_expensive_validation_check): separate expensive
validation checks from cheap ones.
