remote-curl: accept compressed responses with protocol v2

Configure curl to accept compressed responses when using protocol v2 by
setting `CURLOPT_ENCODING` to "", which indicates that curl should send
an "Accept-Encoding" header with all supported compression encodings.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote-curl.c

@@ -1259,6 +1259,7 @@ static int proxy_request(struct proxy_state *p)
 
 	slot = get_active_slot();
 
+	curl_easy_setopt(slot->curl, CURLOPT_ENCODING, "");
 	curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
 	curl_easy_setopt(slot->curl, CURLOPT_POST, 1);
 	curl_easy_setopt(slot->curl, CURLOPT_URL, p->service_url);