qrexec-client: do not prepare event loop for VM -> VM calls

For a VM -> VM service call, no local program will be run and the main
event loop will not be entered.  Therefore, preparing for the main loop
to run is unnecessary.  This also clarifies what actually does and does
not need to be done for VM -> VM calls.

Author: DemiMarie

daemon/qrexec-client.c

@@ -693,10 +693,6 @@ int main(int argc, char **argv)
             wait_connection_end = s;
         else
             close(s);
-        set_remote_domain(domname);
-        struct buffer stdin_buffer;
-        buffer_init(&stdin_buffer);
-        prepare_ret = prepare_local_fds(local_cmdline, &stdin_buffer);
         if (request_id) {
             s = connect_unix_socket(src_domain_id_str);
             send_service_connect(s, request_id, data_domain, data_port);
@@ -709,6 +705,10 @@ int main(int argc, char **argv)
                 poll(fds, 1, -1);
             }
         } else {
+            set_remote_domain(domname);
+            struct buffer stdin_buffer;
+            buffer_init(&stdin_buffer);
+            prepare_ret = prepare_local_fds(local_cmdline, &stdin_buffer);
             data_vchan = libvchan_server_init(data_domain, data_port,
                     VCHAN_BUFFER_SIZE, VCHAN_BUFFER_SIZE);
             if (!data_vchan) {