fpta: subtree-pull libmdbx upstream (stable/0.1, mdbx_dbi_open_ex)
fpta: subtree-pull libmdbx upstream (stable/0.1, mdbx_dbi_open_ex)

Merge commit 'd2b8c669aa39410865eda6550cb2a67a7c100c31'

leo-yuriev/libfpta,leo-yuriev/libfpta