test_process.rb: File.realpath directly

* test/ruby/test_process.rb (with_tmpchdir): use File.realpath
  directly, no need to depend on pathname.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41699 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_process.rb

@@ -1,6 +1,5 @@
 require 'test/unit'
 require 'tempfile'
-require 'pathname'
 require 'timeout'
 require_relative 'envutil'
 require 'rbconfig'
@@ -28,7 +27,7 @@ class TestProcess < Test::Unit::TestCase
 
   def with_tmpchdir
     Dir.mktmpdir {|d|
-      d = Pathname.new(d).realpath.to_s
+      d = File.realpath(d)
       Dir.chdir(d) {
         yield d
       }