common/exechelp: Provide a way to wait for multiple processes.
* common/exechelp-posix.c (gnupg_wait_process): Generalize to 'gnupg_wait_processes'. * common/exechelp-w32.c (gnupg_wait_process): Likewise. * common/exechelp-w32ce.c (gnupg_wait_process): New function stub. * common/exechelp.h (gnupg_wait_process): New prototype.
- Signed-off-by: Justus Winter <justus@g10code.com>