agent: Tell the Pinentry the client's pid.
* configure.ac: Check for SO_PEERCRED et al. * agent/agent.h (server_control_s): Add field 'client_pid'. * agent/command.c (start_command_handler): Set CLIENT_PID. * agent/command-ssh.c (get_client_pid): New. (start_command_handler_ssh): Set CLIENT_PID. * agent/call-pinentry.c (start_pinentry): Tell Pinentry the client-pid.
- Signed-off-by: Werner Koch <wk@gnupg.org>