Auto merge of #7222 - xanderio:master, r=alexcrichton

Auto merge of #7222 - xanderio:master, r=alexcrichton

enable progress bar for FreeBSD

As FreeBSD uses a unsigned long for the IOCTL syscall this code would
previously fail to compile. Adding a call to into() fixes this problem.

This code should still work on other platfroms as into() is able to
'convert' an u32 into a u32.

Also change the cfg attributes so that the working code is used.

This may also work on other not yet supported platforms, but it was not
tested.