btrfs: remove pointless out labels from send.c

btrfs: remove pointless out labels from send.c

Some functions (process_extent(), process_recorded_refs_if_needed(),
changed_inode(), compare_refs() and changed_cb()) have an 'out' label that
does nothing but return, making it pointless. Simplify this by removing
the label and returning instead of gotos plus setting the 'ret' variable.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>