Fixed failure of NDB config retrieval. 1. Made sure that base64 string is terminated with NUL. 2. Made calculation of needed size for base64 string exact. Added checks in test for the above two fixes.
Fixed failure of NDB config retrieval.
1. Made sure that base64 string is terminated with NUL.
2. Made calculation of needed size for base64 string exact.
Added checks in test for the above two fixes.


mysys/base64.c:
  Made sure that base64 string is terminated with NUL.
  Made calculation of needed size for base64 string exact.
  Added checks in test for the above two fixes.

natsys/mariadb_10.2,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,davidl-zend/zenddbi,ollie314/server,slanterns/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,ollie314/server,ollie314/server,natsys/mariadb_10.2,ollie314/server,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,flynn1973/mariadb-aix,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2