Btrfs-progs: receive, allow to continue after errors happen

Btrfs-progs: receive, allow to continue after errors happen

Due to either bugs in send (kernel) that generate a command against
a wrong path for example, or transient errors on the receiving side,
we stopped processing the send stream immediately and exited with
an error.

It's often desirable to continue processing the send stream even if an
error happens while processing a single command from the send stream.

This change just adds a --max-errors <N> parameter, whose default value
is 1 (preserving current behaviour), that allows to tolerate N errors
before stopping. A value of 0 means to never stop no matter how many
errors we get into while processing the send stream. Regardless of its
value, errors are always printed to stderr when they happen, just like
before this change.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.cz>