Fixed RT 938 having to do with SIOCGIFCONF on Linux. We now do a first

Fixed RT 938 having to do with SIOCGIFCONF on Linux. We now do a first
pass in which we pass a null pointer for the buffer, and we will get
back the length of the buffer we should allocate. This is because
if you pass in a buffer that is too small, Linux (unlike other OSes)
will not tell you that it is too small by returning a length greater
than the length you passed in.