tracing: send_sigqueue() needs trace_signal_generate() too

Add trace_signal_generate() into send_sigqueue().

send_sigqueue() is very similar to __send_signal(), just it uses
the preallocated info. It should do the same wrt tracing.

Reported-by: Seiji Aguchi <saguchi@redhat.com>
Reviewed-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>