2)MDEV-4581 (it will be implemented at mdev-4682)

Please check this mdev-4682 too, i sent a patch via github, there's an option that should be implemented at compile time to turn stats on/off i didn't checked how to implement it yet, if anyone could help me :)

it must set a macro 

#define QUERY_CACHE_QC_INFO_PLUGIN 1

at "configure" time, maybe via cmake gui or something like it

maybe i should change QUERY_CACHE_QC_INFO_PLUGIN to QUERY_CACHE_INCLUDE_STATS to easier understand of macro definitions, help is wellcome here
--