clarify errors when listeners fail to bind
When using multiple listeners, the log messages can be
potentially misleading as to which listener fails to bind:
Before:
INFO -- : unlinking existing socket=/tmp/unicorn.sock
INFO -- : listening on addr=/tmp/unicorn.sock fd=3
unicorn/socket_helper.rb:110:in `initialize': Permission denied - bind(2) (Errno::EACCES)
After:
INFO -- : unlinking existing socket=/tmp/openxdms.sock
INFO -- : listening on addr=/tmp/openxdms.sock fd=3
FATAL -- : error adding listener addr=0.0.0.0:84
unicorn/socket_helper.rb:110:in `initialize': Permission denied - bind(2) (Errno::EACCES)