osd/OSDMap: stop encoding osd_state with >8 bits wide states only for old client

osd/OSDMap: stop encoding osd_state with >8 bits wide states only for old client

In a8fb39b5 we extended Incremental's new_state to 32 bits wide
instead of 8. However, if we intend to flip those > 8 bits wide flags
only (e.g., the per-osd CEPH_OSD_NOOUT/NOIN flag), we'll end
up encoding a zeroed new_state into the Incremental map, which'll
be mis-interpreted as osd-down by old clients.

Fix by skipping encoding osd_states with the extended(> 256) flags
only. They simply can not be understood by those clients and will
get ignored anyway.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>