Curl_pgrsDone: return int and acknowledge return code

Since Curl_pgrsDone() itself calls Curl_pgrsUpdate() which may return an
abort instruction or similar we need to return that info back and
subsequently properly handle return codes from Curl_pgrsDone() where
used.

(Spotted by a Coverity scan)

lib/ssh.c

@@ -2820,7 +2820,8 @@ static CURLcode ssh_done(struct connectdata *conn, CURLcode status)
 
   if(sftp_scp)
     Curl_safefree(sftp_scp->path);
-  Curl_pgrsDone(conn);
+  if(Curl_pgrsDone(conn))
+    return CURLE_ABORTED_BY_CALLBACK;
 
   conn->data->req.keepon = 0; /* clear all bits */
   return result;