test_scanf.rb: use tmpefile

* test/scanf/test_scanf.rb (TestIOScanf): use different name for
  each tests, to get rid of weird errors on Windows.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45193 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_scanf.rb: include arguments in names

* test/scanf/test_scanf.rb (ScanfTests#tests): remove duplicated
  tests.

* test/scanf/test_scanf.rb (ScanfTests#each_test): include test
  arguments in test names.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45194 b2dd03c8-39d4-4d8f-98ff-823fe69b080e