simple patch for portsnap to use wget

[Luca Ferrari]

I also tried using HTTP_PROXY and HTTP_PROXY_AUTH and it did not work,
or maybe I don't get how to configure them:

HTTP_PROXY=host:port
HTTP_PROXY_AUTH=base:user:pass

and either

HTTP_PROXY=http://host:port
HTTP_PROXY_AUTH=base:user:pass

In both cases however the error message is different: now it simply
gives up reaching the servers, so there is no formal error on the
downloaded file.

Luca