thorium_message_cache: add cache miss count and cache hit count

The actor message cache subsystem allows an actor to reuse an old
reply message received in response to a previous request message.

This patch adds runtime statistics about these message cache hit and miss
counts.

Without CONFIG_VISITOR_INCREASE_LOCALITY:

thorium_message_cache_print_profile... cache_miss_rate 0.500259 cache_hit_rate 0.499741 total 44341
thorium_message_cache_print_profile... cache_miss_rate 0.500179 cache_hit_rate 0.499821 total 44664
thorium_message_cache_print_profile... cache_miss_rate 0.500140 cache_hit_rate 0.499860 total 53611
thorium_message_cache_print_profile... cache_miss_rate 0.500215 cache_hit_rate 0.499785 total 53463
thorium_message_cache_print_profile... cache_miss_rate 0.500263 cache_hit_rate 0.499737 total 55107
thorium_message_cache_print_profile... cache_miss_rate 0.500245 cache_hit_rate 0.499755 total 55035
thorium_message_cache_print_profile... cache_miss_rate 0.500248 cache_hit_rate 0.499752 total 68676
thorium_message_cache_print_profile... cache_miss_rate 0.500349 cache_hit_rate 0.499651 total 68730
thorium_message_cache_print_profile... cache_miss_rate 0.500292 cache_hit_rate 0.499708 total 68588
thorium_message_cache_print_profile... cache_miss_rate 0.500131 cache_hit_rate 0.499869 total 68764

With CONFIG_VISITOR_INCREASE_LOCALITY:

thorium_message_cache_print_profile... cache_miss_rate 0.194101 cache_hit_rate 0.805899 total 51092
thorium_message_cache_print_profile... cache_miss_rate 0.194985 cache_hit_rate 0.805015 total 51404
thorium_message_cache_print_profile... cache_miss_rate 0.199235 cache_hit_rate 0.800765 total 54413
thorium_message_cache_print_profile... cache_miss_rate 0.198509 cache_hit_rate 0.801491 total 54310
thorium_message_cache_print_profile... cache_miss_rate 0.194712 cache_hit_rate 0.805288 total 51553
thorium_message_cache_print_profile... cache_miss_rate 0.195325 cache_hit_rate 0.804675 total 51427
thorium_message_cache_print_profile... cache_miss_rate 0.198564 cache_hit_rate 0.801436 total 54315
thorium_message_cache_print_profile... cache_miss_rate 0.199548 cache_hit_rate 0.800452 total 54483
thorium_message_cache_print_profile... cache_miss_rate 0.198468 cache_hit_rate 0.801532 total 54311
thorium_message_cache_print_profile... cache_miss_rate 0.198016 cache_hit_rate 0.801984 total 54223

Link: https://github.com/GeneAssembly/biosal/issues/836
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>