Fix: consumer: incorrect size zmalloc

Also, check return value.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: kernel-consumer: double-close

check for -1 out_fd

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: lttng: memory leak in snapshot record command

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>