Fix mysql-test-run w.r.t NDB

"export A=var" is bash feature
instead do "A=var; export A"

mysql-test/mysql-test-run.sh

@@ -1450,9 +1450,11 @@ then
   then
     echo "Starting ndbcluster"
     ./ndb/ndbcluster --port-base=$NDBCLUSTER_PORT --small --diskless --initial --data-dir=$MYSQL_TEST_DIR/var || exit 1
-    export NDB_CONNECTSTRING="host=localhost:$NDBCLUSTER_PORT"
+    NDB_CONNECTSTRING="host=localhost:$NDBCLUSTER_PORT"
+    export NDB_CONNECTSTRING
   else
-    export NDB_CONNECTSTRING="$USE_RUNNING_NDBCLUSTER"
+    NDB_CONNECTSTRING="$USE_RUNNING_NDBCLUSTER"
+    export NDB_CONNECTSTRING
     echo "Using ndbcluster at $NDB_CONNECTSTRING"
   fi
   fi

mysql-test/ndb/ndbcluster.sh

@@ -86,7 +86,6 @@ fs_name_1=$fs_ndb/node-1-fs
 fs_name_2=$fs_ndb/node-2-fs
 
 NDB_HOME=
-export NDB_CONNECTSTRING
 if [ ! -x $fsdir ]; then
   echo "$fsdir missing"
   exit 1
@@ -102,7 +101,8 @@ fi
 
 ndb_host="localhost"
 ndb_mgmd_port=$port_base
-export NDB_CONNECTSTRING="host=$ndb_host:$ndb_mgmd_port"
+NDB_CONNECTSTRING="host=$ndb_host:$ndb_mgmd_port"
+export NDB_CONNECTSTRING
 
 start_default_ndbcluster() {