wininet: Make resolving hostnames thread safe.

[Hans Leidekker]

On Saturday 24 May 2008 20:04:14 Rob Shearman wrote:

> In the long term it would be better to use getaddrinfo instead of
> gethostbyname/gethostbyname_r, but that's too big a change for 1.0.

My thoughts exactly. I looked at getaddrinfo first but realized that
using it means writing new code, so I opted for copying a tried solution
from winsock.

 -Hans