[ruby/logger] Prefer require_relative, it's a little bit faster.

https://github.com/ruby/logger/commit/1e2aab4bea

lib/logger.rb

@@ -11,11 +11,12 @@
 # A simple system for logging messages.  See Logger for more documentation.
 
 require 'monitor'
-require 'logger/version'
-require 'logger/formatter'
-require 'logger/log_device'
-require 'logger/severity'
-require 'logger/errors'
+
+require_relative 'logger/version'
+require_relative 'logger/formatter'
+require_relative 'logger/log_device'
+require_relative 'logger/severity'
+require_relative 'logger/errors'
 
 # == Description
 #

lib/logger/log_device.rb

@@ -1,4 +1,4 @@
-require 'logger/period'
+require_relative 'period'
 
 class Logger
   # Device used for logging messages.