Prevent creation of directory named '-p' on Windows
Prevent creation of directory named '-p' on Windows

`tools.make_dir` used `mkdir -p <name>` while `-p` [is not an existing switch](https://docs.microsoft.com/windows-server/administration/windows-commands/mkdir) on Windows. The switch is also not necessary because plain `mkdir` on Windows also creates intermediate directories.
luarocks/luarocks,luarocks/luarocks,luarocks/luarocks