Fix srp.cpp:815 leak

Thanks @Zeno-

src/client.cpp

@@ -974,6 +974,7 @@ void Client::deleteAuthData()
 		case AUTH_MECHANISM_NONE:
 			break;
 	}
+	m_chosen_auth_mech = AUTH_MECHANISM_NONE;
 }
 
 
@@ -1060,7 +1061,6 @@ void Client::startAuth(AuthMechanism chosen_auth_mechanism)
 
 			NetworkPacket resp_pkt(TOSERVER_SRP_BYTES_A, 0);
 			resp_pkt << std::string(bytes_A, len_A) << based_on;
-			free(bytes_A);
 			Send(&resp_pkt);
 			break;
 		}