Removing two more compilation warnings.

sql/slave.cc:
  Guard declaration of variable to avoid "unused variable" warning.
sql/sql_repl.cc:
  Guard declaration of variable to avoid "unused variable" warning.

sql/slave.cc

@@ -52,7 +52,9 @@ ulonglong relay_log_space_limit = 0;
 
 int disconnect_slave_event_count = 0, abort_slave_event_count = 0;
 int events_till_abort = -1;
+#ifndef DBUG_OFF
 static int events_till_disconnect = -1;
+#endif
 
 typedef enum { SLAVE_THD_IO, SLAVE_THD_SQL} SLAVE_THD_TYPE;
 

sql/sql_repl.cc

@@ -22,7 +22,9 @@
 
 int max_binlog_dump_events = 0; // unlimited
 my_bool opt_sporadic_binlog_dump_fail = 0;
+#ifndef DBUG_OFF
 static int binlog_dump_count = 0;
+#endif
 
 /*
     fake_rotate_event() builds a fake (=which does not exist physically in any