Remnants from embedded server was found in ha_ndbcluster_connection.cc.
The define EMBEDDED_LIBRARY is still used to conditionally compile code.

Remove usage of EMBEDDED_LIBRARY define.

Also clean up the usage of external variables from mysqld.cc to make
those more explicit, they should really not be used directly.

Change-Id: Ie91a18effb05d60e96c4647a0795146c941904a4