ssa_signal_handler.c: Return an error if add2line can't find a function name

run_add2line function skips garbage from add2line utility.
For a skipped frame, it didn't print a line into backtrace, but
returned success. As result, the frame disappeared from the trace.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa_signal_handler.c: Add frame number to back trace line

In case of add2line utility failure, a frame number in
backtrace line was absent.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa_signal_handler.c: Remove ssa_signal_handler before calling abort()

abort will send SIGABRT. It may cause a race in ssa_signal_handler.
In any case, an application is going to exit. We don't need to handle
SIGABRT sent from abort(); leave it to default signal handler
to do its job.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>