mdbx: backport - mdb_env_copyfd2(): Don't abort on SIGPIPE (ITS#8504).
mdbx: backport - mdb_env_copyfd2(): Don't abort on SIGPIPE (ITS#8504).

Return EPIPE instead.
Never clear mc_error, we could lose a failure in the other thread.

Change-Id: Ief08803ed56293309f07be116e69123c10907e77

leo-yuriev/libfpta,leo-yuriev/libfpta