WL#2851: ndb_mgm should retain command history on exit

Affects: Server-5.1   —   Status: Complete   —   Priority: Medium

The ndb_mgm process should retain command history on exit just like the mysql
client does. This allows users to see what was done in previous sessions and
also can reduce time spent retyping commonly used commands.
Per Stewart:
"took about 10 minutes when bored one day. trivial patch, in 5.1... 
IIRC there was a bug report that got it documented."

No further HLS needed.
Per Stewart:
"took about 10 minutes when bored one day. trivial patch, in 5.1... 
IIRC there was a bug report that got it documented."

No further LLD needed.