The text-version of "KILL CONNECTION" command is now supported. To keep the
overhead low, only minimal parsing is done on the query. The query
needs to start in the beginning of the mysql-packet, have no comments
and have limited whitespace as the total length of the query is limited.
Both "KILL 123" and "KILL CONNECTION 123" are accepted.
"KILL QUERY 123" is also accepted but not acted on, as it requires larger
changes.