assertion fails but time.to_s equals.
  (assert_same_entry): use assert_equal_time.

* test/fileutils/test_fileutils.rb (test_install): use
  assert_equal_time.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13973 b2dd03c8-39d4-4d8f-98ff-823fe69b080e