Use __FILE__ for wasm

`/dev/null` is not available on wasm.

Author: nobu

lib/logger/log_device.rb

@@ -223,7 +223,7 @@ def shift_log_period(period_end)
   end
 end
 
-File.open(IO::NULL) do |f|
+File.open(__FILE__) do |f|
   File.new(f.fileno, autoclose: false, path: "").path
 rescue IOError
   module PathAttr               # :nodoc: