Check for missing files in the Addr2Line constructor
Check for missing files in the Addr2Line constructor

I cannot reproduce subprocess throwing an IOError with python2 or
python3. What I was getting on missing file was
_addr2line.stdout.readline returning an empty line.

This patch implements what the existing comment suggests: test on the
destructor.

Signed-off-by: Rafael Ávila de Espíndola <1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>

scylladb/seastar,cloudius-systems/seastar,scylladb/seastar,syuu1228/seastar,scylladb/seastar,dreamsxin/seastar,dreamsxin/seastar,cloudius-systems/seastar,syuu1228/seastar,dreamsxin/seastar,avikivity/seastar,syuu1228/seastar,avikivity/seastar,cloudius-systems/seastar,avikivity/seastar