net: don't concatenate strings in debug logging

Not necessary, not a good idea.

PR-URL: https://github.com/nodejs/node/pull/12342
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/net.js

@@ -1007,7 +1007,7 @@ function lookupAndConnect(self, options) {
     dnsopts.hints = dns.ADDRCONFIG;
   }
 
-  debug('connect: find host ' + host);
+  debug('connect: find host', host);
   debug('connect: dns options', dnsopts);
   self._host = host;
   var lookup = options.lookup || dns.lookup;
@@ -1183,7 +1183,7 @@ function createServerHandle(address, port, addressType, fd) {
       handle = createHandle(fd);
     } catch (e) {
       // Not a fd we can listen on.  This will trigger an error.
-      debug('listen invalid fd=' + fd + ': ' + e.message);
+      debug('listen invalid fd=%d:', fd, e.message);
       return uv.UV_EINVAL;
     }
     handle.open(fd);
@@ -1204,7 +1204,7 @@ function createServerHandle(address, port, addressType, fd) {
   }
 
   if (address || port || isTCP) {
-    debug('bind to ' + (address || 'anycast'));
+    debug('bind to', address || 'any');
     if (!address) {
       // Try binding to ipv6 first
       err = handle.bind6('::', port);