signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal

Any time siginfo is not stored in the signal queue information is
lost.  Therefore set TRACE_SIGNAL_LOSE_INFO every time the code does
not allocate a signal queue entry, and a queue overflow abort is not
triggered.

Fixes: ba005e1f ("tracepoint: Add signal loss events")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>