monerod: do not log to tmpdir in daemon mode

The logging to /tmp/bitmonero.daemon.stdout.stderr caused segfaults
if the /tmp mount was full (#2851).
Now the daemon is only logging to /tmp/bitmonero.daemon.stdout.stderr
in the debug builds.

src/daemonizer/posix_fork.cpp

@@ -115,6 +115,7 @@ void fork(const std::string & pidfile)
     quit("Unable to open /dev/null");
   }
 
+#ifdef DEBUG_TMPDIR_LOG
   // Send standard output to a log file.
   const char *tmpdir = getenv("TMPDIR");
   if (!tmpdir)
@@ -133,6 +134,7 @@ void fork(const std::string & pidfile)
   {
     quit("Unable to dup output descriptor");
   }
+#endif
 }
 
 } // namespace posix