kbx: Fix a race condition which results no status report.
* kbx/keyboxd.h (kbxd_status_printf): New. * kbx/backend-support.c (be_return_pubkey): Use kbxd_status_printf. * kbx/kbxserver.c (kbxd_status_printf): New. * kbxd_start_command_handler (kbxd_start_command_handler): Don't use set_assuan_context_func, because the function pointer is shared by multiple threads.
- GnuPG-bug-id: T5948
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>