Fix memory leak found by Klocwork

--HG--
extra : convert_revision : 6f1e5e6dd6462f1c35a6bfd601a0f5f8b99410d6

cli-authinteract.c

@@ -131,6 +131,7 @@ void recv_msg_userauth_info_request() {
 		response_len = strlen(response);
 		buf_putstring(ses.writepayload, response, response_len);
 		m_burn(response, response_len);
+		m_free(prompt);
 		m_free(response);
 	}