update code to conform to new linting rules

Signed-off-by: Martin Schurz <Martin.Schurz@t-systems.com>

Author: schurzi

Rakefile

@@ -1,5 +1,6 @@
 #!/usr/bin/env rake
 # encoding: utf-8
+# frozen_string_literal: true
 
 require 'rake/testtask'
 require 'rubocop/rake_task'

controls/php_conf.rb

@@ -1,4 +1,6 @@
 # encoding: utf-8
+# frozen_string_literal: true
+
 #
 # Copyright 2015, Dominik Richter
 # Copyright 2016, Christoph Hartmann

libraries/php.rb

@@ -1,4 +1,6 @@
 # encoding: utf-8
+# frozen_string_literal: true
+
 #
 # Copyright 2016, Christoph Hartmann
 #
@@ -33,6 +35,7 @@ class PHP < Inspec.resource(1)
   "
 
   def initialize(options = {})
+    super
     @options = options
   end
 
@@ -49,13 +52,15 @@ def config(param)
   def extension(extension)
     ext = Class.new do
       def initialize(parent, extension)
+        super
         @parent = parent
         @extension = extension
       end
 
       def loaded?
         cmd = @parent._run("#{@parent._php_executable} --ri '#{@extension}'")
         return true if cmd.exit_status.zero?
+
         false
       end
 
@@ -90,6 +95,7 @@ class PHPConfig < PHP
   "
 
   def initialize(param)
+    super
     warn '[DEPRECATION] `php_config(param)` is deprecated.  Please use `php.config(param)` instead.'
     @param = param
   end
@@ -118,6 +124,7 @@ class PHPExtension < PHP
   "
 
   def initialize(extension)
+    super
     warn '[DEPRECATION] `php_extension(ext)` is deprecated.  Please use `php.extension(ext)` instead.'
     @extension = extension
   end