Replace GC_stats_log_printf with GC_DBG/INFOLOG_PRINTF

Replace GC_stats_log_printf with GC_DBG/INFOLOG_PRINTF
(minimize logging for Android when print_stats is off)

* alloc.c (GC_try_to_collect_inner, GC_stopped_mark,
GC_finish_collection): Use GC_log_printf instead of
GC_stats_log_printf.
* finalize.c (GC_print_finalization_stats): Likewise.
* include/private/gc_priv.h (GC_COND_LOG_PRINTF): Likewise.
* alloc.c (GC_stopped_mark): Use GC_DBGLOG_PRINTF instead of
GC_COND_LOG_PRINTF (useful for Android).
* alloc.c (GC_expand_hp_inner): Reformat comment.
* alloc.c (GC_expand_hp_inner): Use GC_INFOLOG_PRINTF instead of
GC_COND_LOG_PRINTF (useful for Android).
* include/private/gc_priv.h (GC_stats_log_printf): Remove (macro and
prototype).
* include/private/gc_priv.h (GC_DBGLOG_PRINTF, GC_INFOLOG_PRINTF):
New macro (redirecting either to GC_COND_LOG_PRINTF or to
GC_log_printf/GC_info_log_printf if GC_ANDROID_LOG).
* include/private/gc_priv.h (GC_info_log_printf): New prototype (only
if GC_ANDROID_LOG).
* misc.c (GC_stats_log_printf): Rename to GC_info_log_printf.