A) Normal non-proxy HTTP:
- no more "Pragma: no-cache" (this only makes sense to proxies)
B) Non-CONNECT HTTP request over proxy:
- "Pragma: no-cache" is used (like before)
- "Proxy-Connection: Keep-alive" (for older style 1.0-proxies)
C) CONNECT HTTP request over proxy:
- "Host: [name]:[port]"
- "Proxy-Connection: Keep-alive"
also affecting NTLM and Negotiate.) It turned out that if the server responded
with 100 Continue before the initial 401 response, libcurl didn't take care of
the response properly. Test case 245 and 246 added to verify this.