win32/file.c: remove unnecessary code
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54806 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
win32/file.c: remove unnecessary code
scan for the last directory separator.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54806 b2dd03c8-39d4-4d8f-98ff-823fe69b080e