FIX: Close unused handle in child process during reshape restart

FIX: Close unused handle in child process during reshape restart

When array reshape (e.g. raid0->raid5 migration) is restarted during
array assembly, file system placed on this array cannot be mounted until
reshape is finished due to "busy" error.

This is caused when reshape is executed on array for external metadata
and array handle is cloned /forked/ to child process environment but not
closed.

Handle can't be closed before executing Grow_continue() because it is
used later in code.

Close unused handle in child process /reshape_container()/.
It is similar to close fd handle in reshape_array() before calling
manage_reshape()/child_monitor() in Grow.c:2290.

Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>