WL#3127: slave side TCP address binding

It should be possible to specify which IP address to use 
to connect to the master on slave that have multiple 
configured network interfaces with valid routes to the master

Allow
  
  CHANGE MASTER ... MASTER_BIND='address' 

* add variables to store bind address in string form 
  (both global and in master_info structure)

* implement MASTER_BIND option in lexer and parser

* add --master-bind option to mysqld
 NOTE! ^ this is not added since we have removed most  --master-* arguments from
mysqld already and the last one
--master-retry-count are being deprecated / Magnus 20101124

* set MYSQL_OPT_BIND option in connect_to_master()
  if bind address is specified

* extend master.info to store/restore bind address if specified

* add Master_Bind field to SHOW SLAVE STATUS output