This reverts commit 52102f6f (r64238).

It is no longer necessary if we use Tempfile.create in
WEBrick::HTTPAuth::Htgroup#flush (see next commit)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64362 b2dd03c8-39d4-4d8f-98ff-823fe69b080e