fpta: subtree-pull libmdbx upstream (stable 0.1, fix suspend_and_append).
fpta: subtree-pull libmdbx upstream (stable 0.1, fix suspend_and_append).

Merge commit '85b5ca22fec12e0d6be17f682717a79b049ebcdf'

leo-yuriev/libfpta,leo-yuriev/libfpta