Remove deprecated variables/macros from the GC headers.

Remove deprecated variables/macros from the GC headers.

* libguile/deprecated.c (scm_mtrigger, scm_mallocated,
  scm_max_segment_size): New global variables, from gc.c.
  (scm_map_free_list,
  scm_gc_set_debug_check_freelist_x)[GUILE_DEBUG_FREELIST]: New stubs.

* libguile/deprecated.h (scm_mallocated, scm_mtrigger,
  scm_max_segment_size): New declarations.
  (scm_map_free_list,
  scm_gc_set_debug_check_freelist_x)[GUILE_DEBUG_FREELIST]: New
  declarations.

* libguile/gc-malloc.c (scm_i_minyield_malloc): Remove.
  (scm_gc_init_malloc): Remove references to `scm_i_minyield_malloc' and
  `scm_mtrigger'.

* libguile/gc.c (scm_mtrigger, scm_mallocated): Remove.
  (scm_init_storage): Remove reference to `SCM_HEAP_SEG_SIZE'.

* libguile/gc.h (scm_max_segment_size, SCM_SET_FREELIST_LOC,
  SCM_FREELIST_LOC, scm_i_master_freelist, scm_i_master_freelist2,
  scm_mallocated, scm_mtrigger): Remove.
  (scm_map_free_list,
  scm_gc_set_debug_check_freelist_x)[SCM_ENABLE_DEPRECATED &&
  GUILE_DEBUG_FREELIST]: Remove.

* libguile/private-gc.h (SCM_DEFAULT_INIT_HEAP_SIZE_1,
  SCM_DEFAULT_MIN_YIELD_1, SCM_DEFAULT_MIN_YIELD_2,
  DEFAULT_SWEEP_AMOUNT, SCM_DEFAULT_MAX_SEGMENT_SIZE,
  SCM_MIN_HEAP_SEG_SIZE, SCM_HEAP_SEG_SIZE,
  SCM_GC_CARD_BVEC_SIZE_IN_LONGS, SCM_GC_IN_CARD_HEADERP): Remove.
  (scm_getenv_int): Made internal.
  (scm_i_marking, scm_mark_all, scm_i_deprecated_memory_return,
  scm_i_find_heap_calls, scm_gc_init_malloc, scm_gc_init_freelist,
  scm_gc_init_segments, scm_gc_init_mark): Remove declarations.

* libguile/gc-segment-table.c: Remove, finally.