proxy: don't require the trailing slash on WinHTTP

The path is not something that you use for proxies, so make use of the
new optionality of the path when extracting URL parts.

appveyor.yml

@@ -40,9 +40,9 @@ test_script:
     ctest -V -R libgit2_clar-cred_callback
     Start-Job { java -jar $Env:APPVEYOR_BUILD_FOLDER\build\poxyproxy.jar -d --port 8080 --credentials foo:bar }
     ctest -V .
-    $env:GITTEST_REMOTE_PROXY_URL = "http://foo:bar@localhost:8080/"
+    $env:GITTEST_REMOTE_PROXY_URL = "http://foo:bar@localhost:8080"
     .\Debug\libgit2_clar.exe -sonline::clone::proxy_credentials_in_url
-    $env:GITTEST_REMOTE_PROXY_URL = "http://localhost:8080/"
+    $env:GITTEST_REMOTE_PROXY_URL = "http://localhost:8080"
     $env:GITTEST_REMOTE_PROXY_USER = "foo"
     $env:GITTEST_REMOTE_PROXY_PASS = "bar"
     .\Debug\libgit2_clar.exe -sonline::clone::proxy_credentials_request

src/transports/winhttp.c

@@ -388,7 +388,8 @@ static int winhttp_stream_connect(winhttp_stream *s)
 		WINHTTP_PROXY_INFO proxy_info;
 		wchar_t *proxy_wide;
 
-		if ((error = gitno_connection_data_from_url(&t->proxy_connection_data, proxy_url, NULL)) < 0)
+		if ((error = gitno_extract_url_parts(&t->proxy_connection_data.host, &t->proxy_connection_data.port, NULL,
+				&t->proxy_connection_data.user, &t->proxy_connection_data.pass, proxy_url, NULL)) < 0)
 			goto on_error;
 
 		if (t->proxy_connection_data.user && t->proxy_connection_data.pass) {