Fix unbounded heap growth in case of intensive disappearing links usage

Fix unbounded heap growth in case of intensive disappearing links usage

Issue #182 (bdwgc).

* finalize.c (GC_ON_GROW_LOG_SIZE_MIN): New macro.
* finalize.c (GC_grow_table): Rename size_ptr to log_size_ptr in
comment; add entries_ptr argument; add comment; call if log_old_size is
GC_ON_GROW_LOG_SIZE_MIN or bigger then call GC_try_to_collect_inner
and, then, return from the function if the number of entries is less
than 75% of the table capacity.
* finalize.c (GC_register_disappearing_link_inner): Pass
dl_hashtbl->entries pointer to GC_grow_table.
* finalize.c (GC_register_finalizer_inner): Pass GC_fo_entries pointer
to GC_grow_table.