multi: turn Curl_done into file local multi_done

... as it now is used by multi.c only.

lib/ftp.c

@@ -3242,7 +3242,7 @@ static CURLcode ftp_connect(struct connectdata *conn,
  * Input argument is already checked for validity.
  */
 static CURLcode ftp_done(struct connectdata *conn, CURLcode status,
-                              bool premature)
+                         bool premature)
 {
   struct SessionHandle *data = conn->data;
   struct FTP *ftp = data->req.protop;
@@ -3256,11 +3256,6 @@ static CURLcode ftp_done(struct connectdata *conn, CURLcode status,
   const char *path_to_use = data->state.path;
 
   if(!ftp)
-    /* When the easy handle is removed from the multi while libcurl is still
-     * trying to resolve the host name, it seems that the ftp struct is not
-     * yet initialized, but the removal action calls Curl_done() which calls
-     * this function. So we simply return success if no ftp pointer is set.
-     */
     return CURLE_OK;
 
   switch(status) {

lib/http.c

@@ -1434,8 +1434,8 @@ static int https_getsock(struct connectdata *conn,
 #endif /* USE_OPENSSL || USE_GNUTLS || USE_SCHANNEL */
 
 /*
- * Curl_http_done() gets called from Curl_done() after a single HTTP request
- * has been performed.
+ * Curl_http_done() gets called after a single HTTP request has been
+ * performed.
  */
 
 CURLcode Curl_http_done(struct connectdata *conn,

lib/imap.c

@@ -1486,10 +1486,6 @@ static CURLcode imap_done(struct connectdata *conn, CURLcode status,
   (void)premature;
 
   if(!imap)
-    /* When the easy handle is removed from the multi interface while libcurl
-       is still trying to resolve the host name, the IMAP struct is not yet
-       initialized. However, the removal action calls Curl_done() which in
-       turn calls this function, so we simply return success. */
     return CURLE_OK;
 
   if(status) {
@@ -1512,8 +1508,7 @@ static CURLcode imap_done(struct connectdata *conn, CURLcode status,
 
        TODO: when the multi interface is used, this _really_ should be using
        the imap_multi_statemach function but we have no general support for
-       non-blocking DONE operations, not in the multi state machine and with
-       Curl_done() invokes on several places in the code!
+       non-blocking DONE operations!
     */
     if(!result)
       result = imap_block_statemach(conn);