fs: fix fd leak on early readstream destroy

[mafintosh]

Currently the following leaks a file descriptor

var fs = require('fs')

var rs = fs.createReadStream('my-file.txt')

rs.on('close', function() {
  console.log('i am never fired')
})

rs.destroy()

In fact if you call rs.destroy() before open has been emitted in general the read stream never closes.

This PR fixes that by calling .close() when the file descriptor is opened incase the stream has been destroyed in the meanwhile

[mafintosh]

Oh I see this is a dup of #56. Closing.