http: consolidate #ifdefs for curl_multi_remove_handle

I find #ifdefs makes code difficult-to-follow.

An early version of this patch had error checking for
curl_multi_remove_handle calls, but caused some tests (e.g.
t5541) to fail under curl 7.26.0 on old Debian wheezy.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -167,6 +167,13 @@ static void finish_active_slot(struct active_request_slot *slot)
 		slot->callback_func(slot->callback_data);
 }
 
+static void xmulti_remove_handle(struct active_request_slot *slot)
+{
+#ifdef USE_CURL_MULTI
+	curl_multi_remove_handle(curlm, slot->curl);
+#endif
+}
+
 #ifdef USE_CURL_MULTI
 static void process_curl_messages(void)
 {
@@ -182,7 +189,7 @@ static void process_curl_messages(void)
 			       slot->curl != curl_message->easy_handle)
 				slot = slot->next;
 			if (slot != NULL) {
-				curl_multi_remove_handle(curlm, slot->curl);
+				xmulti_remove_handle(slot);
 				slot->curl_result = curl_result;
 				finish_active_slot(slot);
 			} else {
@@ -588,9 +595,7 @@ void http_cleanup(void)
 	while (slot != NULL) {
 		struct active_request_slot *next = slot->next;
 		if (slot->curl != NULL) {
-#ifdef USE_CURL_MULTI
-			curl_multi_remove_handle(curlm, slot->curl);
-#endif
+			xmulti_remove_handle(slot);
 			curl_easy_cleanup(slot->curl);
 		}
 		free(slot);
@@ -851,9 +856,7 @@ static void release_active_slot(struct active_request_slot *slot)
 {
 	closedown_active_slot(slot);
 	if (slot->curl && curl_session_count > min_curl_sessions) {
-#ifdef USE_CURL_MULTI
-		curl_multi_remove_handle(curlm, slot->curl);
-#endif
+		xmulti_remove_handle(slot);
 		curl_easy_cleanup(slot->curl);
 		slot->curl = NULL;
 		curl_session_count--;